/*-------------------------------------------------------------------------
 *
 * prepjointree.c
 *      Planner preprocessing for subqueries and join tree manipulation.
 *
 * NOTE: the intended sequence for invoking these operations is
 *        pull_up_sublinks
 *        inline_set_returning_functions
 *        pull_up_subqueries
 *        flatten_simple_union_all
 *        do expression preprocessing (including flattening JOIN alias vars)
 *        reduce_outer_joins
 *
 *
 * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * This source code file contains modifications made by THL A29 Limited ("Tencent Modifications").
 * All Tencent Modifications are Copyright (C) 2023 THL A29 Limited.
 *
 * IDENTIFICATION
 *      src/backend/optimizer/prep/prepjointree.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "catalog/pg_type.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/clauses.h"
#include "optimizer/placeholder.h"
#include "optimizer/prep.h"
#include "optimizer/subselect.h"
#include "optimizer/tlist.h"
#include "optimizer/var.h"
#include "parser/parse_relation.h"
#include "parser/parsetree.h"
#include "rewrite/rewriteManip.h"
#ifdef PGXC
#include "access/sysattr.h"
#endif


typedef struct pullup_replace_vars_context
{
    PlannerInfo *root;
    List       *targetlist;        /* tlist of subquery being pulled up */
    RangeTblEntry *target_rte;    /* RTE of subquery */
    Relids        relids;            /* relids within subquery, as numbered after
                                 * pullup (set only if target_rte->lateral) */
    bool       *outer_hasSubLinks;    /* -> outer query's hasSubLinks */
    int            varno;            /* varno of subquery */
    bool        need_phvs;        /* do we need PlaceHolderVars? */
    bool        wrap_non_vars;    /* do we need 'em on *all* non-Vars? */
    Node      **rv_cache;        /* cache for results with PHVs */
} pullup_replace_vars_context;

typedef struct reduce_outer_joins_state
{
    Relids        relids;            /* base relids within this subtree */
    bool        contains_outer; /* does subtree contain outer join(s)? */
    List       *sub_states;        /* List of states for subtree components */
} reduce_outer_joins_state;

static Node *pull_up_sublinks_jointree_recurse(PlannerInfo *root, Node *jtnode,
                                  Relids *relids);
static Node *pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node,
                              Node **jtlink1, Relids available_rels1,
                              Node **jtlink2, Relids available_rels2);
static Node *pull_up_subqueries_recurse(PlannerInfo *root, Node *jtnode,
                           JoinExpr *lowest_outer_join,
                           JoinExpr *lowest_nulling_outer_join,
                           AppendRelInfo *containing_appendrel,
                           bool deletion_ok);
static Node *pull_up_simple_subquery(PlannerInfo *root, Node *jtnode,
                        RangeTblEntry *rte,
                        JoinExpr *lowest_outer_join,
                        JoinExpr *lowest_nulling_outer_join,
                        AppendRelInfo *containing_appendrel,
                        bool deletion_ok);
static Node *pull_up_simple_union_all(PlannerInfo *root, Node *jtnode,
                         RangeTblEntry *rte);
static void pull_up_union_leaf_queries(Node *setOp, PlannerInfo *root,
                           int parentRTindex, Query *setOpQuery,
                           int childRToffset);
static void make_setop_translation_list(Query *query, Index newvarno,
                            List **translated_vars);
static bool is_simple_subquery(Query *subquery, RangeTblEntry *rte,
                   JoinExpr *lowest_outer_join,
                   bool deletion_ok);
static Node *pull_up_simple_values(PlannerInfo *root, Node *jtnode,
                      RangeTblEntry *rte);
static bool is_simple_values(PlannerInfo *root, RangeTblEntry *rte,
                 bool deletion_ok);
static bool is_simple_union_all(Query *subquery);
static bool is_simple_union_all_recurse(Node *setOp, Query *setOpQuery,
                            List *colTypes);
static bool is_safe_append_member(Query *subquery);
static bool jointree_contains_lateral_outer_refs(Node *jtnode, bool restricted,
                                     Relids safe_upper_varnos);
static void replace_vars_in_jointree(Node *jtnode,
                         pullup_replace_vars_context *context,
                         JoinExpr *lowest_nulling_outer_join);
static Node *pullup_replace_vars(Node *expr,
                    pullup_replace_vars_context *context);
static Node *pullup_replace_vars_callback(Var *var,
                             replace_rte_variables_context *context);
static Query *pullup_replace_vars_subquery(Query *query,
                             pullup_replace_vars_context *context);
static Node *pull_up_subqueries_cleanup(Node *jtnode);
static reduce_outer_joins_state *reduce_outer_joins_pass1(Node *jtnode);
static void reduce_outer_joins_pass2(Node *jtnode,
                         reduce_outer_joins_state *state,
                         PlannerInfo *root,
                         Relids nonnullable_rels,
                         List *nonnullable_vars,
                         List *forced_null_vars);
static void substitute_multiple_relids(Node *node,
                           int varno, Relids subrelids);
static void fix_append_rel_relids(List *append_rel_list, int varno,
                      Relids subrelids);
static Node *find_jointree_node_for_rel(Node *jtnode, int relid);

#ifdef __OPENTENBASE__
static Node *pull_up_or_sublinks_qual_recurse(PlannerInfo *root, Node *node,
									Node **jtlink,Node **orclauses);
static bool check_pull_up_sublinks_qual_or_recurse(PlannerInfo *root,
									Node *node);

#endif

/*
 * pull_up_sublinks
 *        Attempt to pull up ANY and EXISTS SubLinks to be treated as
 *        semijoins or anti-semijoins.
 *
 * A clause "foo op ANY (sub-SELECT)" can be processed by pulling the
 * sub-SELECT up to become a rangetable entry and treating the implied
 * comparisons as quals of a semijoin.  However, this optimization *only*
 * works at the top level of WHERE or a JOIN/ON clause, because we cannot
 * distinguish whether the ANY ought to return FALSE or NULL in cases
 * involving NULL inputs.  Also, in an outer join's ON clause we can only
 * do this if the sublink is degenerate (ie, references only the nullable
 * side of the join).  In that case it is legal to push the semijoin
 * down into the nullable side of the join.  If the sublink references any
 * nonnullable-side variables then it would have to be evaluated as part
 * of the outer join, which makes things way too complicated.
 *
 * Under similar conditions, EXISTS and NOT EXISTS clauses can be handled
 * by pulling up the sub-SELECT and creating a semijoin or anti-semijoin.
 *
 * This routine searches for such clauses and does the necessary parsetree
 * transformations if any are found.
 *
 * This routine has to run before preprocess_expression(), so the quals
 * clauses are not yet reduced to implicit-AND format, and are not guaranteed
 * to be AND/OR-flat either.  That means we need to recursively search through
 * explicit AND clauses.  We stop as soon as we hit a non-AND item.
 */
void
pull_up_sublinks(PlannerInfo *root)
{
	Node	   *jtnode;
	Relids		relids;

#ifdef __OPENTENBASE__
    /*
     * Look for SubLinks in targetlist, and try to transform them into joins.
     */
    if(enable_pullup_subquery)
    {
        List 		*new_targetList = NIL;
        ListCell 	*lc 			= NULL;
        TargetEntry *entry 			= NULL;
        TargetEntry *new_entry 		= NULL;

        /* Iterate through out the target list */
        foreach(lc, root->parse->targetList)
        {
            entry = (TargetEntry *) lfirst(lc);

            /* Try to convert sublink in targetlist entry to join */
            new_entry = convert_TargetList_sublink_to_join(root, entry);

            if (new_entry)
                new_targetList = lappend(new_targetList, new_entry);
            else
                new_targetList = lappend(new_targetList, entry);
        }

        root->parse->targetList = new_targetList;
    }
#endif

	/* Begin recursion through the jointree */
	jtnode = pull_up_sublinks_jointree_recurse(root,
											   (Node *) root->parse->jointree,
											   &relids);

	/*
	 * root->parse->jointree must always be a FromExpr, so insert a dummy one
	 * if we got a bare RangeTblRef or JoinExpr out of the recursion.
	 */
	if (IsA(jtnode, FromExpr))
		root->parse->jointree = (FromExpr *) jtnode;
	else
		root->parse->jointree = makeFromExpr(list_make1(jtnode), NULL);
}

/*
 * Recurse through jointree nodes for pull_up_sublinks()
 *
 * In addition to returning the possibly-modified jointree node, we return
 * a relids set of the contained rels into *relids.
 */
static Node *
pull_up_sublinks_jointree_recurse(PlannerInfo *root, Node *jtnode,
                                  Relids *relids)
{// #lizard forgives
    if (jtnode == NULL)
    {
        *relids = NULL;
    }
    else if (IsA(jtnode, RangeTblRef))
    {
        int            varno = ((RangeTblRef *) jtnode)->rtindex;

        *relids = bms_make_singleton(varno);
        /* jtnode is returned unmodified */
    }
    else if (IsA(jtnode, FromExpr))
    {
        FromExpr   *f = (FromExpr *) jtnode;
        List       *newfromlist = NIL;
		Node	   *orquals = NULL;
        Relids        frelids = NULL;
        FromExpr   *newf;
        Node       *jtlink;
        ListCell   *l;

        /* First, recurse to process children and collect their relids */
        foreach(l, f->fromlist)
        {
            Node       *newchild;
            Relids        childrelids;

            newchild = pull_up_sublinks_jointree_recurse(root,
                                                         lfirst(l),
                                                         &childrelids);
            newfromlist = lappend(newfromlist, newchild);
            frelids = bms_join(frelids, childrelids);
        }
        /* Build the replacement FromExpr; no quals yet */
        newf = makeFromExpr(newfromlist, NULL);
        /* Set up a link representing the rebuilt jointree */
        jtlink = (Node *) newf;
        /* Now process qual --- all children are available for use */
        newf->quals = pull_up_sublinks_qual_recurse(root, f->quals,
                                                    &jtlink, frelids,
                                                    NULL, NULL);
#ifdef __OPENTENBASE__
		if (enable_pullup_subquery)
		{
			newf->quals = pull_up_or_sublinks_qual_recurse(root, newf->quals, &jtlink, &orquals);
			if (orquals)
			{
				jtlink = (Node *)makeFromExpr(list_make1(jtlink), orquals);
			}
		}
#endif

		/*
		 * Note that the result will be either newf, or a stack of JoinExprs
		 * with newf at the base.  We rely on subsequent optimization steps to
		 * flatten this and rearrange the joins as needed.
		 *
		 * Although we could include the pulled-up subqueries in the returned
		 * relids, there's no need since upper quals couldn't refer to their
		 * outputs anyway.
		 */
		*relids = frelids;
		jtnode = jtlink;
	}
	else if (IsA(jtnode, JoinExpr))
	{
		JoinExpr   *j;
		Relids		leftrelids;
		Relids		rightrelids;
		Node	   *jtlink;

		/*
		 * Make a modifiable copy of join node, but don't bother copying its
		 * subnodes (yet).
		 */
		j = (JoinExpr *) palloc(sizeof(JoinExpr));
		memcpy(j, jtnode, sizeof(JoinExpr));
		jtlink = (Node *) j;

		/* Recurse to process children and collect their relids */
		j->larg = pull_up_sublinks_jointree_recurse(root, j->larg,
													&leftrelids);
		j->rarg = pull_up_sublinks_jointree_recurse(root, j->rarg,
													&rightrelids);

		/*
		 * Now process qual, showing appropriate child relids as available,
		 * and attach any pulled-up jointree items at the right place. In the
		 * inner-join case we put new JoinExprs above the existing one (much
		 * as for a FromExpr-style join).  In outer-join cases the new
		 * JoinExprs must go into the nullable side of the outer join. The
		 * point of the available_rels machinations is to ensure that we only
		 * pull up quals for which that's okay.
		 *
		 * We don't expect to see any pre-existing JOIN_SEMI or JOIN_ANTI
		 * nodes here.
		 */
		switch (j->jointype)
		{
			case JOIN_INNER:
				j->quals = pull_up_sublinks_qual_recurse(root, j->quals,
														 &jtlink,
														 bms_union(leftrelids,
																   rightrelids),
														 NULL, NULL);
				break;
			case JOIN_LEFT:
#ifdef __OPENTENBASE__
			case JOIN_SEMI:
            case JOIN_LEFT_SCALAR:
            case JOIN_LEFT_SEMI:
#endif
				j->quals = pull_up_sublinks_qual_recurse(root, j->quals,
														 &j->rarg,
														 rightrelids,
														 NULL, NULL);
				break;
			case JOIN_FULL:
				/* can't do anything with full-join quals */
				break;
			case JOIN_RIGHT:
				j->quals = pull_up_sublinks_qual_recurse(root, j->quals,
														 &j->larg,
														 leftrelids,
														 NULL, NULL);
				break;
			default:
				elog(ERROR, "unrecognized join type: %d",
					 (int) j->jointype);
				break;
		}

		/*
		 * Although we could include the pulled-up subqueries in the returned
		 * relids, there's no need since upper quals couldn't refer to their
		 * outputs anyway.  But we *do* need to include the join's own rtindex
		 * because we haven't yet collapsed join alias variables, so upper
		 * levels would mistakenly think they couldn't use references to this
		 * join.
		 */
		*relids = bms_join(leftrelids, rightrelids);
		if (j->rtindex)
			*relids = bms_add_member(*relids, j->rtindex);
		jtnode = jtlink;
	}
	else
		elog(ERROR, "unrecognized node type: %d",
			 (int) nodeTag(jtnode));
	return jtnode;
}
#ifdef __OPENTENBASE__

static bool
check_pull_up_sublinks_qual_or_recurse(PlannerInfo *root, Node *node)
{
	if (node == NULL)
		return true;

	if (IsA(node, SubLink))
	{
		SubLink *sublink = (SubLink *)node;
		Query   *subselect = (Query *)sublink->subselect;

		if (sublink->subLinkType == EXISTS_SUBLINK)
		{
			if (!check_or_exist_sublink_pullupable(root, node))
				return false;

			if(subselect && subselect->jointree && subselect->jointree->quals)
				return check_or_exist_qual_pullupable(root, subselect->jointree->quals);

			return false;
		}

		return false;
	}
	else if (or_clause(node))
	{
		ListCell *l;

		foreach (l, ((BoolExpr *)node)->args)
		{
			if (!check_pull_up_sublinks_qual_or_recurse(root, (Node *)lfirst(l)))
				return false;
		}

		return true;
	}
	return false;
}

static Node *
pull_up_or_sublinks_qual_recurse(PlannerInfo *root, Node *node, Node **jtlink, Node **orquals)
{
	if (node == NULL)
		return NULL;

	if (and_clause(node))
	{
		List *newclauses = NIL;
		ListCell *l;

		foreach (l, ((BoolExpr *)node)->args)
		{
			Node *oldclause = (Node *)lfirst(l);
			Node *newclause;
			newclause = pull_up_or_sublinks_qual_recurse(root,
														 oldclause,
														 jtlink,
														 orquals);
			if (newclause)
				newclauses = lappend(newclauses, newclause);
		}

		if (newclauses == NIL)
			return NULL;
		else if (list_length(newclauses) == 1)
			return (Node *)linitial(newclauses);
		else
			return (Node *)make_andclause(newclauses);
	}
	else if (or_clause(node))
	{
		Node *new_qual = NULL;
		List *newclauses = NIL;
		ListCell *l;

		foreach (l, ((BoolExpr *)node)->args)
		{
			if (!check_pull_up_sublinks_qual_or_recurse(root, (Node *)lfirst(l)))
				return node;
		}

		foreach (l, ((BoolExpr *)node)->args)
		{
			Node *oldclause = (Node *)lfirst(l);
			List *resclauses;
			resclauses = convert_OR_EXIST_sublink_to_join_recurse(root,
																  oldclause,
																  jtlink);
			if (resclauses)
				newclauses = list_concat(newclauses, resclauses);
		}

		new_qual = (Node *)make_orclause(newclauses);

		if (*orquals == NULL)
		{
			*orquals = new_qual;
		}
		else
		{
			BoolExpr *expr = (BoolExpr *)(*orquals);
			if (expr->boolop == OR_EXPR)
			{
				*orquals = (Node *)make_andclause(list_make2(*orquals,
															 new_qual));
			}
			else
			{
				expr->args = lappend(expr->args, new_qual);
			}
		}
		return NULL;
	}
	return node;
}

#endif

/*
 * Recurse through top-level qual nodes for pull_up_sublinks()
 *
 * jtlink1 points to the link in the jointree where any new JoinExprs should
 * be inserted if they reference available_rels1 (i.e., available_rels1
 * denotes the relations present underneath jtlink1).  Optionally, jtlink2 can
 * point to a second link where new JoinExprs should be inserted if they
 * reference available_rels2 (pass NULL for both those arguments if not used).
 * Note that SubLinks referencing both sets of variables cannot be optimized.
 * If we find multiple pull-up-able SubLinks, they'll get stacked onto jtlink1
 * and/or jtlink2 in the order we encounter them.  We rely on subsequent
 * optimization to rearrange the stack if appropriate.
 *
 * Returns the replacement qual node, or NULL if the qual should be removed.
 */
static Node *
pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node,
                              Node **jtlink1, Relids available_rels1,
                              Node **jtlink2, Relids available_rels2)
{// #lizard forgives
    if (node == NULL)
        return NULL;
    if (IsA(node, SubLink))
    {
        SubLink    *sublink = (SubLink *) node;
        JoinExpr   *j;
        Relids        child_rels;

        /* Is it a convertible ANY or EXISTS clause? */
        if (sublink->subLinkType == ANY_SUBLINK)
        {
#ifdef __OPENTENBASE__
            if ((j = convert_ANY_sublink_to_join(root, sublink,
                                                 available_rels1, false)) != NULL)
#else
            if ((j = convert_ANY_sublink_to_join(root, sublink,
                                                 available_rels1)) != NULL)
#endif
            {
                /* Yes; insert the new join node into the join tree */
                j->larg = *jtlink1;
                *jtlink1 = (Node *) j;
                /* Recursively process pulled-up jointree nodes */
                j->rarg = pull_up_sublinks_jointree_recurse(root,
                                                            j->rarg,
                                                            &child_rels);

                /*
                 * Now recursively process the pulled-up quals.  Any inserted
                 * joins can get stacked onto either j->larg or j->rarg,
                 * depending on which rels they reference.
                 */
                j->quals = pull_up_sublinks_qual_recurse(root,
                                                         j->quals,
                                                         &j->larg,
                                                         available_rels1,
                                                         &j->rarg,
                                                         child_rels);
                /* Return NULL representing constant TRUE */
                return NULL;
            }
#ifdef __OPENTENBASE__
            if (available_rels2 != NULL &&
                (j = convert_ANY_sublink_to_join(root, sublink,
                                                 available_rels2, false)) != NULL)
#else
            if (available_rels2 != NULL &&
                (j = convert_ANY_sublink_to_join(root, sublink,
                                                 available_rels2)) != NULL)
#endif
            {
                /* Yes; insert the new join node into the join tree */
                j->larg = *jtlink2;
                *jtlink2 = (Node *) j;
                /* Recursively process pulled-up jointree nodes */
                j->rarg = pull_up_sublinks_jointree_recurse(root,
                                                            j->rarg,
                                                            &child_rels);

                /*
                 * Now recursively process the pulled-up quals.  Any inserted
                 * joins can get stacked onto either j->larg or j->rarg,
                 * depending on which rels they reference.
                 */
                j->quals = pull_up_sublinks_qual_recurse(root,
                                                         j->quals,
                                                         &j->larg,
                                                         available_rels2,
                                                         &j->rarg,
                                                         child_rels);
                /* Return NULL representing constant TRUE */
                return NULL;
            }
        }
        else if (sublink->subLinkType == EXISTS_SUBLINK)
        {
            if ((j = convert_EXISTS_sublink_to_join(root, sublink, false,
                                                    available_rels1)) != NULL)
            {
                /* Yes; insert the new join node into the join tree */
                j->larg = *jtlink1;
                *jtlink1 = (Node *) j;
                /* Recursively process pulled-up jointree nodes */
                j->rarg = pull_up_sublinks_jointree_recurse(root,
                                                            j->rarg,
                                                            &child_rels);

                /*
                 * Now recursively process the pulled-up quals.  Any inserted
                 * joins can get stacked onto either j->larg or j->rarg,
                 * depending on which rels they reference.
                 */
                j->quals = pull_up_sublinks_qual_recurse(root,
                                                         j->quals,
                                                         &j->larg,
                                                         available_rels1,
                                                         &j->rarg,
                                                         child_rels);
                /* Return NULL representing constant TRUE */
                return NULL;
            }
            if (available_rels2 != NULL &&
                (j = convert_EXISTS_sublink_to_join(root, sublink, false,
                                                    available_rels2)) != NULL)
            {
                /* Yes; insert the new join node into the join tree */
                j->larg = *jtlink2;
                *jtlink2 = (Node *) j;
                /* Recursively process pulled-up jointree nodes */
                j->rarg = pull_up_sublinks_jointree_recurse(root,
                                                            j->rarg,
                                                            &child_rels);

                /*
                 * Now recursively process the pulled-up quals.  Any inserted
                 * joins can get stacked onto either j->larg or j->rarg,
                 * depending on which rels they reference.
                 */
                j->quals = pull_up_sublinks_qual_recurse(root,
                                                         j->quals,
                                                         &j->larg,
                                                         available_rels2,
                                                         &j->rarg,
                                                         child_rels);
                /* Return NULL representing constant TRUE */
                return NULL;
            }
        }
#ifdef __OPENTENBASE__
        else if (sublink->subLinkType == ALL_SUBLINK)
        {        
            if ((j = convert_ALL_sublink_to_join(root, sublink,
                                                    available_rels1)) != NULL)
            {
                /* Yes; insert the new join node into the join tree */
                j->larg = *jtlink1;
                *jtlink1 = (Node *) j;
                /* Recursively process pulled-up jointree nodes */
                j->rarg = pull_up_sublinks_jointree_recurse(root,
                                                            j->rarg,
                                                            &child_rels);

                /*
                 * Now recursively process the pulled-up quals.  Any inserted
                 * joins can get stacked onto either j->larg or j->rarg,
                 * depending on which rels they reference.
                 */
                j->quals = pull_up_sublinks_qual_recurse(root,
                                                         j->quals,
                                                         &j->larg,
                                                         available_rels1,
                                                         &j->rarg,
                                                         child_rels);
                /* Return NULL representing constant TRUE */
                return NULL;
            }
            if (available_rels2 != NULL &&
                (j = convert_ALL_sublink_to_join(root, sublink,
                                                    available_rels2)) != NULL)
            {
                /* Yes; insert the new join node into the join tree */
                j->larg = *jtlink2;
                *jtlink2 = (Node *) j;
                /* Recursively process pulled-up jointree nodes */
                j->rarg = pull_up_sublinks_jointree_recurse(root,
                                                            j->rarg,
                                                            &child_rels);

                /*
                 * Now recursively process the pulled-up quals.  Any inserted
                 * joins can get stacked onto either j->larg or j->rarg,
                 * depending on which rels they reference.
                 */
                j->quals = pull_up_sublinks_qual_recurse(root,
                                                         j->quals,
                                                         &j->larg,
                                                         available_rels2,
                                                         &j->rarg,
                                                         child_rels);
                /* Return NULL representing constant TRUE */
                return NULL;
            }
        }
#endif
        /* Else return it unmodified */
        return node;
    }
    if (not_clause(node))
    {
        /* If the immediate argument of NOT is EXISTS, try to convert */
        SubLink    *sublink = (SubLink *) get_notclausearg((Expr *) node);
        JoinExpr   *j;
        Relids        child_rels;

        if (sublink && IsA(sublink, SubLink))
        {
            if (sublink->subLinkType == EXISTS_SUBLINK)
            {
                if ((j = convert_EXISTS_sublink_to_join(root, sublink, true,
                                                        available_rels1)) != NULL)
                {
                    /* Yes; insert the new join node into the join tree */
                    j->larg = *jtlink1;
                    *jtlink1 = (Node *) j;
                    /* Recursively process pulled-up jointree nodes */
                    j->rarg = pull_up_sublinks_jointree_recurse(root,
                                                                j->rarg,
                                                                &child_rels);

                    /*
                     * Now recursively process the pulled-up quals.  Because
                     * we are underneath a NOT, we can't pull up sublinks that
                     * reference the left-hand stuff, but it's still okay to
                     * pull up sublinks referencing j->rarg.
                     */
                    j->quals = pull_up_sublinks_qual_recurse(root,
                                                             j->quals,
                                                             &j->rarg,
                                                             child_rels,
                                                             NULL, NULL);
                    /* Return NULL representing constant TRUE */
                    return NULL;
                }
                if (available_rels2 != NULL &&
                    (j = convert_EXISTS_sublink_to_join(root, sublink, true,
                                                        available_rels2)) != NULL)
                {
                    /* Yes; insert the new join node into the join tree */
                    j->larg = *jtlink2;
                    *jtlink2 = (Node *) j;
                    /* Recursively process pulled-up jointree nodes */
                    j->rarg = pull_up_sublinks_jointree_recurse(root,
                                                                j->rarg,
                                                                &child_rels);

                    /*
                     * Now recursively process the pulled-up quals.  Because
                     * we are underneath a NOT, we can't pull up sublinks that
                     * reference the left-hand stuff, but it's still okay to
                     * pull up sublinks referencing j->rarg.
                     */
                    j->quals = pull_up_sublinks_qual_recurse(root,
                                                             j->quals,
                                                             &j->rarg,
                                                             child_rels,
                                                             NULL, NULL);
                    /* Return NULL representing constant TRUE */
                    return NULL;
                }
            }
#ifdef __OPENTENBASE__
            else if (sublink->subLinkType == ANY_SUBLINK)
            {
                if ((j = convert_ANY_sublink_to_join(root, sublink,
                                                     available_rels1, true)) != NULL)
                {
                    /* Yes; insert the new join node into the join tree */
                    j->larg = *jtlink1;
                    *jtlink1 = (Node *) j;
                    /* Recursively process pulled-up jointree nodes */
                    j->rarg = pull_up_sublinks_jointree_recurse(root,
                                                                j->rarg,
                                                                &child_rels);

                    /*
                     * Now recursively process the pulled-up quals.  Any inserted
                     * joins can get stacked onto either j->larg or j->rarg,
                     * depending on which rels they reference.
                     */
                    j->quals = pull_up_sublinks_qual_recurse(root,
                                                             j->quals,
                                                             &j->larg,
                                                             available_rels1,
                                                             &j->rarg,
                                                             child_rels);
                    /* Return NULL representing constant TRUE */
                    return NULL;
                }
                if (available_rels2 != NULL &&
                    (j = convert_ANY_sublink_to_join(root, sublink,
                                                 available_rels2, true)) != NULL)
                {
                    /* Yes; insert the new join node into the join tree */
                    j->larg = *jtlink2;
                    *jtlink2 = (Node *) j;
                    /* Recursively process pulled-up jointree nodes */
                    j->rarg = pull_up_sublinks_jointree_recurse(root,
                                                                j->rarg,
                                                                &child_rels);

                    /*
                     * Now recursively process the pulled-up quals.  Any inserted
                     * joins can get stacked onto either j->larg or j->rarg,
                     * depending on which rels they reference.
                     */
                    j->quals = pull_up_sublinks_qual_recurse(root,
                                                             j->quals,
                                                             &j->larg,
                                                             available_rels2,
                                                             &j->rarg,
                                                             child_rels);
                    /* Return NULL representing constant TRUE */
                    return NULL;
                }
            }
#endif
        }
        /* Else return it unmodified */
        return node;
    }
    if (and_clause(node))
    {
        /* Recurse into AND clause */
        List       *newclauses = NIL;
        ListCell   *l;

        foreach(l, ((BoolExpr *) node)->args)
        {
            Node       *oldclause = (Node *) lfirst(l);
            Node       *newclause;

            newclause = pull_up_sublinks_qual_recurse(root,
                                                      oldclause,
                                                      jtlink1,
                                                      available_rels1,
                                                      jtlink2,
                                                      available_rels2);
            if (newclause)
                newclauses = lappend(newclauses, newclause);
        }
        /* We might have got back fewer clauses than we started with */
        if (newclauses == NIL)
            return NULL;
        else if (list_length(newclauses) == 1)
            return (Node *) linitial(newclauses);
        else
            return (Node *) make_andclause(newclauses);
    }
#ifdef __OPENTENBASE__
    /*
      * another case handled here:
      * select * from a where a.num op (select max(b.num) from b where a.id op b.id and ...) ;
      * transform to:
      * select * from a, (select id, max(num) as num from b group by id) temp 
      * where a.num op temp.num and a.id op temp.id and ...;
      * and this can be kind of join.
         */
    if (OpExpr_clause(node))
    {
        JoinExpr   *j;
		FromExpr   *from;
		Node       *filter;
        Relids        child_rels;
        
        if ((j = convert_EXPR_sublink_to_join(root, (OpExpr *)node,
												available_rels1, &filter)) != NULL)
        {
            /* Yes; insert the new join node into the join tree */
            j->larg = *jtlink1;

			from = makeNode(FromExpr);
			from->quals = filter;
			from->fromlist = list_make1(j);

			*jtlink1 = (Node *)from;

            /* Recursively process pulled-up jointree nodes */
            j->rarg = pull_up_sublinks_jointree_recurse(root,
                                                        j->rarg,
                                                        &child_rels);

            /*
             * Now recursively process the pulled-up quals.  Any inserted
             * joins can get stacked onto either j->larg or j->rarg,
             * depending on which rels they reference.
             */
            j->quals = pull_up_sublinks_qual_recurse(root,
                                                     j->quals,
                                                     &j->larg,
                                                     available_rels1,
                                                     &j->rarg,
                                                     child_rels);
            /* Return NULL representing constant TRUE */
            return NULL;
        }

        if (available_rels2 != NULL &&
                    (j = convert_EXPR_sublink_to_join(root, (OpExpr *)node,
												 available_rels2, &filter)) != NULL)
        {
            /* Yes; insert the new join node into the join tree */
            j->larg = *jtlink2;

			from = makeNode(FromExpr);
			from->quals = filter;
			from->fromlist = list_make1(j);

			*jtlink2 = (Node *)from;

            /* Recursively process pulled-up jointree nodes */
            j->rarg = pull_up_sublinks_jointree_recurse(root,
                                                        j->rarg,
                                                        &child_rels);

            /*
             * Now recursively process the pulled-up quals.  Any inserted
             * joins can get stacked onto either j->larg or j->rarg,
             * depending on which rels they reference.
             */
            j->quals = pull_up_sublinks_qual_recurse(root,
                                                     j->quals,
                                                     &j->larg,
                                                     available_rels2,
                                                     &j->rarg,
                                                     child_rels);
            /* Return NULL representing constant TRUE */
            return NULL;
        }
     }
#endif
    /* Stop if not an AND */
    return node;
}

/*
 * inline_set_returning_functions
 *        Attempt to "inline" set-returning functions in the FROM clause.
 *
 * If an RTE_FUNCTION rtable entry invokes a set-returning function that
 * contains just a simple SELECT, we can convert the rtable entry to an
 * RTE_SUBQUERY entry exposing the SELECT directly.  This is especially
 * useful if the subquery can then be "pulled up" for further optimization,
 * but we do it even if not, to reduce executor overhead.
 *
 * This has to be done before we have started to do any optimization of
 * subqueries, else any such steps wouldn't get applied to subqueries
 * obtained via inlining.  However, we do it after pull_up_sublinks
 * so that we can inline any functions used in SubLink subselects.
 *
 * Like most of the planner, this feels free to scribble on its input data
 * structure.
 */
void
inline_set_returning_functions(PlannerInfo *root)
{
    ListCell   *rt;

    foreach(rt, root->parse->rtable)
    {
        RangeTblEntry *rte = (RangeTblEntry *) lfirst(rt);

        if (rte->rtekind == RTE_FUNCTION)
        {
            Query       *funcquery;

            /* Check safety of expansion, and expand if possible */
            funcquery = inline_set_returning_function(root, rte);
            if (funcquery)
            {
                /* Successful expansion, replace the rtable entry */
                rte->rtekind = RTE_SUBQUERY;
                rte->subquery = funcquery;
                rte->functions = NIL;
            }
        }
    }
}

/*
 * pull_up_subqueries
 *        Look for subqueries in the rangetable that can be pulled up into
 *        the parent query.  If the subquery has no special features like
 *        grouping/aggregation then we can merge it into the parent's jointree.
 *        Also, subqueries that are simple UNION ALL structures can be
 *        converted into "append relations".
 */
void
pull_up_subqueries(PlannerInfo *root)
{
    /* Top level of jointree must always be a FromExpr */
    Assert(IsA(root->parse->jointree, FromExpr));
    /* Reset flag saying we need a deletion cleanup pass */
    root->hasDeletedRTEs = false;
    /* Recursion starts with no containing join nor appendrel */
    root->parse->jointree = (FromExpr *)
        pull_up_subqueries_recurse(root, (Node *) root->parse->jointree,
                                   NULL, NULL, NULL, false);
    /* Apply cleanup phase if necessary */
    if (root->hasDeletedRTEs)
        root->parse->jointree = (FromExpr *)
            pull_up_subqueries_cleanup((Node *) root->parse->jointree);
    Assert(IsA(root->parse->jointree, FromExpr));
}

/*
 * pull_up_subqueries_recurse
 *        Recursive guts of pull_up_subqueries.
 *
 * This recursively processes the jointree and returns a modified jointree.
 * Or, if it's valid to drop the current node from the jointree completely,
 * it returns NULL.
 *
 * If this jointree node is within either side of an outer join, then
 * lowest_outer_join references the lowest such JoinExpr node; otherwise
 * it is NULL.  We use this to constrain the effects of LATERAL subqueries.
 *
 * If this jointree node is within the nullable side of an outer join, then
 * lowest_nulling_outer_join references the lowest such JoinExpr node;
 * otherwise it is NULL.  This forces use of the PlaceHolderVar mechanism for
 * references to non-nullable targetlist items, but only for references above
 * that join.
 *
 * If we are looking at a member subquery of an append relation,
 * containing_appendrel describes that relation; else it is NULL.
 * This forces use of the PlaceHolderVar mechanism for all non-Var targetlist
 * items, and puts some additional restrictions on what can be pulled up.
 *
 * deletion_ok is TRUE if the caller can cope with us returning NULL for a
 * deletable leaf node (for example, a VALUES RTE that could be pulled up).
 * If it's FALSE, we'll avoid pullup in such cases.
 *
 * A tricky aspect of this code is that if we pull up a subquery we have
 * to replace Vars that reference the subquery's outputs throughout the
 * parent query, including quals attached to jointree nodes above the one
 * we are currently processing!  We handle this by being careful not to
 * change the jointree structure while recursing: no nodes other than leaf
 * RangeTblRef entries and entirely-empty FromExprs will be replaced or
 * deleted.  Also, we can't turn pullup_replace_vars loose on the whole
 * jointree, because it'll return a mutated copy of the tree; we have to
 * invoke it just on the quals, instead.  This behavior is what makes it
 * reasonable to pass lowest_outer_join and lowest_nulling_outer_join as
 * pointers rather than some more-indirect way of identifying the lowest
 * OJs.  Likewise, we don't replace append_rel_list members but only their
 * substructure, so the containing_appendrel reference is safe to use.
 *
 * Because of the rule that no jointree nodes with substructure can be
 * replaced, we cannot fully handle the case of deleting nodes from the tree:
 * when we delete one child of a JoinExpr, we need to replace the JoinExpr
 * with a FromExpr, and that can't happen here.  Instead, we set the
 * root->hasDeletedRTEs flag, which tells pull_up_subqueries() that an
 * additional pass over the tree is needed to clean up.
 */
static Node *
pull_up_subqueries_recurse(PlannerInfo *root, Node *jtnode,
						   JoinExpr *lowest_outer_join,
						   JoinExpr *lowest_nulling_outer_join,
						   AppendRelInfo *containing_appendrel,
						   bool deletion_ok)
{
	Assert(jtnode != NULL);
	if (IsA(jtnode, RangeTblRef))
	{
		int			varno = ((RangeTblRef *) jtnode)->rtindex;
		RangeTblEntry *rte = rt_fetch(varno, root->parse->rtable);

		/*
		 * Is this a subquery RTE, and if so, is the subquery simple enough to
		 * pull up?
		 *
		 * If we are looking at an append-relation member, we can't pull it up
		 * unless is_safe_append_member says so.
		 */
		if (rte->rtekind == RTE_SUBQUERY &&
			is_simple_subquery(rte->subquery, rte,
							   lowest_outer_join, deletion_ok) &&
			(containing_appendrel == NULL ||
			 is_safe_append_member(rte->subquery)))
			return pull_up_simple_subquery(root, jtnode, rte,
										   lowest_outer_join,
										   lowest_nulling_outer_join,
										   containing_appendrel,
										   deletion_ok);

		/*
		 * Alternatively, is it a simple UNION ALL subquery?  If so, flatten
		 * into an "append relation".
		 *
		 * It's safe to do this regardless of whether this query is itself an
		 * appendrel member.  (If you're thinking we should try to flatten the
		 * two levels of appendrel together, you're right; but we handle that
		 * in set_append_rel_pathlist, not here.)
		 */
		if (rte->rtekind == RTE_SUBQUERY &&
			is_simple_union_all(rte->subquery))
			return pull_up_simple_union_all(root, jtnode, rte);

		/*
		 * Or perhaps it's a simple VALUES RTE?
		 *
		 * We don't allow VALUES pullup below an outer join nor into an
		 * appendrel (such cases are impossible anyway at the moment).
		 */
		if (rte->rtekind == RTE_VALUES &&
			lowest_outer_join == NULL &&
			containing_appendrel == NULL &&
			is_simple_values(root, rte, deletion_ok))
			return pull_up_simple_values(root, jtnode, rte);

		/* Otherwise, do nothing at this node. */
	}
	else if (IsA(jtnode, FromExpr))
	{
		FromExpr   *f = (FromExpr *) jtnode;
		bool		have_undeleted_child = false;
		ListCell   *l;

		Assert(containing_appendrel == NULL);

		/*
		 * If the FromExpr has quals, it's not deletable even if its parent
		 * would allow deletion.
		 */
		if (f->quals)
			deletion_ok = false;

		foreach(l, f->fromlist)
		{
			/*
			 * In a non-deletable FromExpr, we can allow deletion of child
			 * nodes so long as at least one child remains; so it's okay
			 * either if any previous child survives, or if there's more to
			 * come.  If all children are deletable in themselves, we'll force
			 * the last one to remain unflattened.
			 *
			 * As a separate matter, we can allow deletion of all children of
			 * the top-level FromExpr in a query, since that's a special case
			 * anyway.
			 */
			bool		sub_deletion_ok = (deletion_ok ||
										   have_undeleted_child ||
										   lnext(l) != NULL ||
										   f == root->parse->jointree);

			lfirst(l) = pull_up_subqueries_recurse(root, lfirst(l),
												   lowest_outer_join,
												   lowest_nulling_outer_join,
												   NULL,
												   sub_deletion_ok);
			if (lfirst(l) != NULL)
				have_undeleted_child = true;
		}

		if (deletion_ok && !have_undeleted_child)
		{
			/* OK to delete this FromExpr entirely */
			root->hasDeletedRTEs = true;	/* probably is set already */
			return NULL;
		}
	}
	else if (IsA(jtnode, JoinExpr))
	{
		JoinExpr   *j = (JoinExpr *) jtnode;

		Assert(containing_appendrel == NULL);
		/* Recurse, being careful to tell myself when inside outer join */
		switch (j->jointype)
		{
			case JOIN_INNER:

				/*
				 * INNER JOIN can allow deletion of either child node, but not
				 * both.  So right child gets permission to delete only if
				 * left child didn't get removed.
				 */
				j->larg = pull_up_subqueries_recurse(root, j->larg,
													 lowest_outer_join,
													 lowest_nulling_outer_join,
													 NULL,
													 true);
				j->rarg = pull_up_subqueries_recurse(root, j->rarg,
													 lowest_outer_join,
													 lowest_nulling_outer_join,
													 NULL,
													 j->larg != NULL);
				break;
			case JOIN_LEFT:
			case JOIN_SEMI:
#ifdef __OPENTENBASE__
            case JOIN_LEFT_SCALAR:
            case JOIN_LEFT_SEMI:
#endif
			case JOIN_ANTI:
				j->larg = pull_up_subqueries_recurse(root, j->larg,
													 j,
													 lowest_nulling_outer_join,
													 NULL,
													 false);
				j->rarg = pull_up_subqueries_recurse(root, j->rarg,
													 j,
													 j,
													 NULL,
													 false);
				break;
			case JOIN_FULL:
				j->larg = pull_up_subqueries_recurse(root, j->larg,
													 j,
													 j,
													 NULL,
													 false);
				j->rarg = pull_up_subqueries_recurse(root, j->rarg,
													 j,
													 j,
													 NULL,
													 false);
				break;
			case JOIN_RIGHT:
				j->larg = pull_up_subqueries_recurse(root, j->larg,
													 j,
													 j,
													 NULL,
													 false);
				j->rarg = pull_up_subqueries_recurse(root, j->rarg,
													 j,
													 lowest_nulling_outer_join,
													 NULL,
													 false);
				break;
			default:
				elog(ERROR, "unrecognized join type: %d",
					 (int) j->jointype);
				break;
		}
	}
	else
		elog(ERROR, "unrecognized node type: %d",
			 (int) nodeTag(jtnode));
	return jtnode;
}

/*
 * pull_up_simple_subquery
 *        Attempt to pull up a single simple subquery.
 *
 * jtnode is a RangeTblRef that has been tentatively identified as a simple
 * subquery by pull_up_subqueries.  We return the replacement jointree node,
 * or NULL if the subquery can be deleted entirely, or jtnode itself if we
 * determine that the subquery can't be pulled up after all.
 *
 * rte is the RangeTblEntry referenced by jtnode.  Remaining parameters are
 * as for pull_up_subqueries_recurse.
 */
static Node *
pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
                        JoinExpr *lowest_outer_join,
                        JoinExpr *lowest_nulling_outer_join,
                        AppendRelInfo *containing_appendrel,
                        bool deletion_ok)
{// #lizard forgives
    Query       *parse = root->parse;
    int            varno = ((RangeTblRef *) jtnode)->rtindex;
    Query       *subquery;
    PlannerInfo *subroot;
    int            rtoffset;
    pullup_replace_vars_context rvcontext;
    ListCell   *lc;

    /*
     * Need a modifiable copy of the subquery to hack on.  Even if we didn't
     * sometimes choose not to pull up below, we must do this to avoid
     * problems if the same subquery is referenced from multiple jointree
     * items (which can't happen normally, but might after rule rewriting).
     */
    subquery = copyObject(rte->subquery);

    /*
     * Create a PlannerInfo data structure for this subquery.
     *
     * NOTE: the next few steps should match the first processing in
     * subquery_planner().  Can we refactor to avoid code duplication, or
     * would that just make things uglier?
     */
    subroot = makeNode(PlannerInfo);
    subroot->parse = subquery;
    subroot->glob = root->glob;
    subroot->query_level = root->query_level;
    subroot->parent_root = root->parent_root;
    subroot->plan_params = NIL;
    subroot->outer_params = NULL;
    subroot->planner_cxt = CurrentMemoryContext;
    subroot->init_plans = NIL;
    subroot->cte_plan_ids = NIL;
    subroot->multiexpr_params = NIL;
    subroot->eq_classes = NIL;
    subroot->append_rel_list = NIL;
    subroot->rowMarks = NIL;
    memset(subroot->upper_rels, 0, sizeof(subroot->upper_rels));
    memset(subroot->upper_targets, 0, sizeof(subroot->upper_targets));
    subroot->processed_tlist = NIL;
    subroot->grouping_map = NULL;
    subroot->minmax_aggs = NIL;
    subroot->qual_security_level = 0;
#ifdef _MLS_
    subroot->hasClsPolicy = false;
#endif
    subroot->hasInheritedTarget = false;
    subroot->hasRecursion = false;
    subroot->wt_param_id = -1;
    subroot->recursiveOk = true;
    subroot->non_recursive_path = NULL;

    /* No CTEs to worry about */
    Assert(subquery->cteList == NIL);

    /*
     * Pull up any SubLinks within the subquery's quals, so that we don't
     * leave unoptimized SubLinks behind.
     */
    if (subquery->hasSubLinks)
        pull_up_sublinks(subroot);

    /*
     * Similarly, inline any set-returning functions in its rangetable.
     */
    inline_set_returning_functions(subroot);

    /*
     * Recursively pull up the subquery's subqueries, so that
     * pull_up_subqueries' processing is complete for its jointree and
     * rangetable.
     *
     * Note: it's okay that the subquery's recursion starts with NULL for
     * containing-join info, even if we are within an outer join in the upper
     * query; the lower query starts with a clean slate for outer-join
     * semantics.  Likewise, we needn't pass down appendrel state.
     */
    pull_up_subqueries(subroot);

    /*
     * Now we must recheck whether the subquery is still simple enough to pull
     * up.  If not, abandon processing it.
     *
     * We don't really need to recheck all the conditions involved, but it's
     * easier just to keep this "if" looking the same as the one in
     * pull_up_subqueries_recurse.
     */
    if (is_simple_subquery(subquery, rte,
                           lowest_outer_join, deletion_ok) &&
        (containing_appendrel == NULL || is_safe_append_member(subquery)))
    {
        /* good to go */
    }
    else
    {
        /*
         * Give up, return unmodified RangeTblRef.
         *
         * Note: The work we just did will be redone when the subquery gets
         * planned on its own.  Perhaps we could avoid that by storing the
         * modified subquery back into the rangetable, but I'm not gonna risk
         * it now.
         */
        return jtnode;
    }

    /*
     * We must flatten any join alias Vars in the subquery's targetlist,
     * because pulling up the subquery's subqueries might have changed their
     * expansions into arbitrary expressions, which could affect
     * pullup_replace_vars' decisions about whether PlaceHolderVar wrappers
     * are needed for tlist entries.  (Likely it'd be better to do
     * flatten_join_alias_vars on the whole query tree at some earlier stage,
     * maybe even in the rewriter; but for now let's just fix this case here.)
     */
    subquery->targetList = (List *)
        flatten_join_alias_vars(subroot, (Node *) subquery->targetList);

    /*
     * Adjust level-0 varnos in subquery so that we can append its rangetable
     * to upper query's.  We have to fix the subquery's append_rel_list as
     * well.
     */
    rtoffset = list_length(parse->rtable);
    OffsetVarNodes((Node *) subquery, rtoffset, 0);
    OffsetVarNodes((Node *) subroot->append_rel_list, rtoffset, 0);

    /*
     * Upper-level vars in subquery are now one level closer to their parent
     * than before.
     */
    IncrementVarSublevelsUp((Node *) subquery, -1, 1);
    IncrementVarSublevelsUp((Node *) subroot->append_rel_list, -1, 1);

    /*
     * The subquery's targetlist items are now in the appropriate form to
     * insert into the top query, but if we are under an outer join then
     * non-nullable items and lateral references may have to be turned into
     * PlaceHolderVars.  If we are dealing with an appendrel member then
     * anything that's not a simple Var has to be turned into a
     * PlaceHolderVar.  Set up required context data for pullup_replace_vars.
     */
    rvcontext.root = root;
    rvcontext.targetlist = subquery->targetList;
    rvcontext.target_rte = rte;
    if (rte->lateral)
        rvcontext.relids = get_relids_in_jointree((Node *) subquery->jointree,
                                                  true);
    else                        /* won't need relids */
        rvcontext.relids = NULL;
    rvcontext.outer_hasSubLinks = &parse->hasSubLinks;
    rvcontext.varno = varno;
    rvcontext.need_phvs = (lowest_nulling_outer_join != NULL ||
                           containing_appendrel != NULL);
    rvcontext.wrap_non_vars = (containing_appendrel != NULL);
    /* initialize cache array with indexes 0 .. length(tlist) */
    rvcontext.rv_cache = palloc0((list_length(subquery->targetList) + 1) *
                                 sizeof(Node *));

    /*
     * Replace all of the top query's references to the subquery's outputs
     * with copies of the adjusted subtlist items, being careful not to
     * replace any of the jointree structure. (This'd be a lot cleaner if we
     * could use query_tree_mutator.)  We have to use PHVs in the targetList,
     * returningList, and havingQual, since those are certainly above any
     * outer join.  replace_vars_in_jointree tracks its location in the
     * jointree and uses PHVs or not appropriately.
     */
    parse->targetList = (List *)
        pullup_replace_vars((Node *) parse->targetList, &rvcontext);
    parse->returningList = (List *)
        pullup_replace_vars((Node *) parse->returningList, &rvcontext);
    if (parse->onConflict)
    {
        parse->onConflict->onConflictSet = (List *)
            pullup_replace_vars((Node *) parse->onConflict->onConflictSet,
                                &rvcontext);
        parse->onConflict->onConflictWhere =
            pullup_replace_vars(parse->onConflict->onConflictWhere,
                                &rvcontext);

        /*
         * We assume ON CONFLICT's arbiterElems, arbiterWhere, exclRelTlist
         * can't contain any references to a subquery
         */
    }
    replace_vars_in_jointree((Node *) parse->jointree, &rvcontext,
                             lowest_nulling_outer_join);
    Assert(parse->setOperations == NULL);
    parse->havingQual = pullup_replace_vars(parse->havingQual, &rvcontext);

    /*
     * Replace references in the translated_vars lists of appendrels. When
     * pulling up an appendrel member, we do not need PHVs in the list of the
     * parent appendrel --- there isn't any outer join between. Elsewhere, use
     * PHVs for safety.  (This analysis could be made tighter but it seems
     * unlikely to be worth much trouble.)
     */
    foreach(lc, root->append_rel_list)
    {
        AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(lc);
        bool        save_need_phvs = rvcontext.need_phvs;

        if (appinfo == containing_appendrel)
            rvcontext.need_phvs = false;
        appinfo->translated_vars = (List *)
            pullup_replace_vars((Node *) appinfo->translated_vars, &rvcontext);
        rvcontext.need_phvs = save_need_phvs;
    }

    /*
     * Replace references in the joinaliasvars lists of join RTEs.
     *
     * You might think that we could avoid using PHVs for alias vars of joins
     * below lowest_nulling_outer_join, but that doesn't work because the
     * alias vars could be referenced above that join; we need the PHVs to be
     * present in such references after the alias vars get flattened.  (It
     * might be worth trying to be smarter here, someday.)
     */
    foreach(lc, parse->rtable)
    {
        RangeTblEntry *otherrte = (RangeTblEntry *) lfirst(lc);

        if (otherrte->rtekind == RTE_JOIN)
            otherrte->joinaliasvars = (List *)
                pullup_replace_vars((Node *) otherrte->joinaliasvars,
                                    &rvcontext);
    }

    /*
     * If the subquery had a LATERAL marker, propagate that to any of its
     * child RTEs that could possibly now contain lateral cross-references.
     * The children might or might not contain any actual lateral
     * cross-references, but we have to mark the pulled-up child RTEs so that
     * later planner stages will check for such.
     */
    if (rte->lateral)
    {
        foreach(lc, subquery->rtable)
        {
            RangeTblEntry *child_rte = (RangeTblEntry *) lfirst(lc);

            switch (child_rte->rtekind)
            {
                case RTE_RELATION:
                    if (child_rte->tablesample)
                        child_rte->lateral = true;
                    break;
                case RTE_SUBQUERY:
                case RTE_FUNCTION:
                case RTE_VALUES:
                case RTE_TABLEFUNC:
                    child_rte->lateral = true;
                    break;
                case RTE_JOIN:
                case RTE_CTE:
#ifdef XCP    
                case RTE_REMOTE_DUMMY:
#endif
                case RTE_NAMEDTUPLESTORE:
                    /* these can't contain any lateral references */
                    break;
            }
        }
    }

    /*
     * Now append the adjusted rtable entries to upper query. (We hold off
     * until after fixing the upper rtable entries; no point in running that
     * code on the subquery ones too.)
     */
    parse->rtable = list_concat(parse->rtable, subquery->rtable);

    /*
     * Pull up any FOR UPDATE/SHARE markers, too.  (OffsetVarNodes already
     * adjusted the marker rtindexes, so just concat the lists.)
     */
    parse->rowMarks = list_concat(parse->rowMarks, subquery->rowMarks);

    /*
     * We also have to fix the relid sets of any PlaceHolderVar nodes in the
     * parent query.  (This could perhaps be done by pullup_replace_vars(),
     * but it seems cleaner to use two passes.)  Note in particular that any
     * PlaceHolderVar nodes just created by pullup_replace_vars() will be
     * adjusted, so having created them with the subquery's varno is correct.
     *
     * Likewise, relids appearing in AppendRelInfo nodes have to be fixed. We
     * already checked that this won't require introducing multiple subrelids
     * into the single-slot AppendRelInfo structs.
     */
    if (parse->hasSubLinks || root->glob->lastPHId != 0 ||
        root->append_rel_list)
    {
        Relids        subrelids;

        subrelids = get_relids_in_jointree((Node *) subquery->jointree, false);
        substitute_multiple_relids((Node *) parse, varno, subrelids);
        fix_append_rel_relids(root->append_rel_list, varno, subrelids);
    }

    /*
     * And now add subquery's AppendRelInfos to our list.
     */
    root->append_rel_list = list_concat(root->append_rel_list,
                                        subroot->append_rel_list);

    /*
     * We don't have to do the equivalent bookkeeping for outer-join info,
     * because that hasn't been set up yet.  placeholder_list likewise.
     */
    Assert(root->join_info_list == NIL);
    Assert(subroot->join_info_list == NIL);
    Assert(root->placeholder_list == NIL);
    Assert(subroot->placeholder_list == NIL);

    /*
     * Miscellaneous housekeeping.
     *
     * Although replace_rte_variables() faithfully updated parse->hasSubLinks
     * if it copied any SubLinks out of the subquery's targetlist, we still
     * could have SubLinks added to the query in the expressions of FUNCTION
     * and VALUES RTEs copied up from the subquery.  So it's necessary to copy
     * subquery->hasSubLinks anyway.  Perhaps this can be improved someday.
     */
    parse->hasSubLinks |= subquery->hasSubLinks;

    /* If subquery had any RLS conditions, now main query does too */
    parse->hasRowSecurity |= subquery->hasRowSecurity;

    /*
     * subquery won't be pulled up if it hasAggs, hasWindowFuncs, or
     * hasTargetSRFs, so no work needed on those flags
     */

    /*
     * Return the adjusted subquery jointree to replace the RangeTblRef entry
     * in parent's jointree; or, if we're flattening a subquery with empty
     * FROM list, return NULL to signal deletion of the subquery from the
     * parent jointree (and set hasDeletedRTEs to ensure cleanup later).
     */
    if (subquery->jointree->fromlist == NIL)
    {
        Assert(deletion_ok);
        Assert(subquery->jointree->quals == NULL);
        root->hasDeletedRTEs = true;
        return NULL;
    }

    return (Node *) subquery->jointree;
}

/*
 * pull_up_simple_union_all
 *        Pull up a single simple UNION ALL subquery.
 *
 * jtnode is a RangeTblRef that has been identified as a simple UNION ALL
 * subquery by pull_up_subqueries.  We pull up the leaf subqueries and
 * build an "append relation" for the union set.  The result value is just
 * jtnode, since we don't actually need to change the query jointree.
 */
static Node *
pull_up_simple_union_all(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte)
{
    int            varno = ((RangeTblRef *) jtnode)->rtindex;
    Query       *subquery = rte->subquery;
    int            rtoffset = list_length(root->parse->rtable);
    List       *rtable;

    /*
     * Make a modifiable copy of the subquery's rtable, so we can adjust
     * upper-level Vars in it.  There are no such Vars in the setOperations
     * tree proper, so fixing the rtable should be sufficient.
     */
    rtable = copyObject(subquery->rtable);

    /*
     * Upper-level vars in subquery are now one level closer to their parent
     * than before.  We don't have to worry about offsetting varnos, though,
     * because the UNION leaf queries can't cross-reference each other.
     */
    IncrementVarSublevelsUp_rtable(rtable, -1, 1);

    /*
     * If the UNION ALL subquery had a LATERAL marker, propagate that to all
     * its children.  The individual children might or might not contain any
     * actual lateral cross-references, but we have to mark the pulled-up
     * child RTEs so that later planner stages will check for such.
     */
    if (rte->lateral)
    {
        ListCell   *rt;

        foreach(rt, rtable)
        {
            RangeTblEntry *child_rte = (RangeTblEntry *) lfirst(rt);

            Assert(child_rte->rtekind == RTE_SUBQUERY);
            child_rte->lateral = true;
        }
    }

    /*
     * Append child RTEs to parent rtable.
     */
    root->parse->rtable = list_concat(root->parse->rtable, rtable);

    /*
     * Recursively scan the subquery's setOperations tree and add
     * AppendRelInfo nodes for leaf subqueries to the parent's
     * append_rel_list.  Also apply pull_up_subqueries to the leaf subqueries.
     */
    Assert(subquery->setOperations);
    pull_up_union_leaf_queries(subquery->setOperations, root, varno, subquery,
                               rtoffset);

    /*
     * Mark the parent as an append relation.
     */
    rte->inh = true;

    return jtnode;
}

/*
 * pull_up_union_leaf_queries -- recursive guts of pull_up_simple_union_all
 *
 * Build an AppendRelInfo for each leaf query in the setop tree, and then
 * apply pull_up_subqueries to the leaf query.
 *
 * Note that setOpQuery is the Query containing the setOp node, whose tlist
 * contains references to all the setop output columns.  When called from
 * pull_up_simple_union_all, this is *not* the same as root->parse, which is
 * the parent Query we are pulling up into.
 *
 * parentRTindex is the appendrel parent's index in root->parse->rtable.
 *
 * The child RTEs have already been copied to the parent.  childRToffset
 * tells us where in the parent's range table they were copied.  When called
 * from flatten_simple_union_all, childRToffset is 0 since the child RTEs
 * were already in root->parse->rtable and no RT index adjustment is needed.
 */
static void
pull_up_union_leaf_queries(Node *setOp, PlannerInfo *root, int parentRTindex,
                           Query *setOpQuery, int childRToffset)
{
    if (IsA(setOp, RangeTblRef))
    {
        RangeTblRef *rtr = (RangeTblRef *) setOp;
        int            childRTindex;
        AppendRelInfo *appinfo;

        /*
         * Calculate the index in the parent's range table
         */
        childRTindex = childRToffset + rtr->rtindex;

        /*
         * Build a suitable AppendRelInfo, and attach to parent's list.
         */
        appinfo = makeNode(AppendRelInfo);
        appinfo->parent_relid = parentRTindex;
        appinfo->child_relid = childRTindex;
        appinfo->parent_reltype = InvalidOid;
        appinfo->child_reltype = InvalidOid;
        make_setop_translation_list(setOpQuery, childRTindex,
                                    &appinfo->translated_vars);
        appinfo->parent_reloid = InvalidOid;
        root->append_rel_list = lappend(root->append_rel_list, appinfo);

        /*
         * Recursively apply pull_up_subqueries to the new child RTE.  (We
         * must build the AppendRelInfo first, because this will modify it.)
         * Note that we can pass NULL for containing-join info even if we're
         * actually under an outer join, because the child's expressions
         * aren't going to propagate up to the join.  Also, we ignore the
         * possibility that pull_up_subqueries_recurse() returns a different
         * jointree node than what we pass it; if it does, the important thing
         * is that it replaced the child relid in the AppendRelInfo node.
         */
        rtr = makeNode(RangeTblRef);
        rtr->rtindex = childRTindex;
        (void) pull_up_subqueries_recurse(root, (Node *) rtr,
                                          NULL, NULL, appinfo, false);
    }
    else if (IsA(setOp, SetOperationStmt))
    {
        SetOperationStmt *op = (SetOperationStmt *) setOp;

        /* Recurse to reach leaf queries */
        pull_up_union_leaf_queries(op->larg, root, parentRTindex, setOpQuery,
                                   childRToffset);
        pull_up_union_leaf_queries(op->rarg, root, parentRTindex, setOpQuery,
                                   childRToffset);
    }
    else
    {
        elog(ERROR, "unrecognized node type: %d",
             (int) nodeTag(setOp));
    }
}

/*
 * make_setop_translation_list
 *      Build the list of translations from parent Vars to child Vars for
 *      a UNION ALL member.  (At this point it's just a simple list of
 *      referencing Vars, but if we succeed in pulling up the member
 *      subquery, the Vars will get replaced by pulled-up expressions.)
 */
static void
make_setop_translation_list(Query *query, Index newvarno,
                            List **translated_vars)
{
    List       *vars = NIL;
    ListCell   *l;

    foreach(l, query->targetList)
    {
        TargetEntry *tle = (TargetEntry *) lfirst(l);

        if (tle->resjunk)
            continue;

        vars = lappend(vars, makeVarFromTargetEntry(newvarno, tle));
    }

    *translated_vars = vars;
}

/*
 * is_simple_subquery
 *      Check a subquery in the range table to see if it's simple enough
 *      to pull up into the parent query.
 *
 * rte is the RTE_SUBQUERY RangeTblEntry that contained the subquery.
 * (Note subquery is not necessarily equal to rte->subquery; it could be a
 * processed copy of that.)
 * lowest_outer_join is the lowest outer join above the subquery, or NULL.
 * deletion_ok is TRUE if it'd be okay to delete the subquery entirely.
 */
static bool
is_simple_subquery(Query *subquery, RangeTblEntry *rte,
                   JoinExpr *lowest_outer_join,
                   bool deletion_ok)
{// #lizard forgives
    /*
     * Let's just make sure it's a valid subselect ...
     */
    if (!IsA(subquery, Query) ||
        subquery->commandType != CMD_SELECT)
        elog(ERROR, "subquery is bogus");

    /*
     * Can't currently pull up a query with setops (unless it's simple UNION
     * ALL, which is handled by a different code path). Maybe after querytree
     * redesign...
     */
    if (subquery->setOperations)
        return false;

    /*
     * Can't pull up a subquery involving grouping, aggregation, SRFs,
     * sorting, limiting, or WITH.  (XXX WITH could possibly be allowed later)
     *
     * We also don't pull up a subquery that has explicit FOR UPDATE/SHARE
     * clauses, because pullup would cause the locking to occur semantically
     * higher than it should.  Implicit FOR UPDATE/SHARE is okay because in
     * that case the locking was originally declared in the upper query
     * anyway.
     */
    if (subquery->hasAggs ||
        subquery->hasWindowFuncs ||
        subquery->hasTargetSRFs ||
        subquery->groupClause ||
        subquery->groupingSets ||
        subquery->havingQual ||
        subquery->sortClause ||
        subquery->distinctClause ||
        subquery->limitOffset ||
        subquery->limitCount ||
        subquery->hasForUpdate ||
        subquery->cteList)
        return false;

    /*
     * Don't pull up if the RTE represents a security-barrier view; we
     * couldn't prevent information leakage once the RTE's Vars are scattered
     * about in the upper query.
     */
    if (rte->security_barrier)
        return false;

    /*
     * Don't pull up a subquery with an empty jointree, unless it has no quals
     * and deletion_ok is TRUE and we're not underneath an outer join.
     *
     * query_planner() will correctly generate a Result plan for a jointree
     * that's totally empty, but we can't cope with an empty FromExpr
     * appearing lower down in a jointree: we identify join rels via baserelid
     * sets, so we couldn't distinguish a join containing such a FromExpr from
     * one without it.  We can only handle such cases if the place where the
     * subquery is linked is a FromExpr or inner JOIN that would still be
     * nonempty after removal of the subquery, so that it's still identifiable
     * via its contained baserelids.  Safe contexts are signaled by
     * deletion_ok.
     *
     * But even in a safe context, we must keep the subquery if it has any
     * quals, because it's unclear where to put them in the upper query.
     *
     * Also, we must forbid pullup if such a subquery is underneath an outer
     * join, because then we might need to wrap its output columns with
     * PlaceHolderVars, and the PHVs would then have empty relid sets meaning
     * we couldn't tell where to evaluate them.  (This test is separate from
     * the deletion_ok flag for possible future expansion: deletion_ok tells
     * whether the immediate parent site in the jointree could cope, not
     * whether we'd have PHV issues.  It's possible this restriction could be
     * fixed by letting the PHVs use the relids of the parent jointree item,
     * but that complication is for another day.)
     *
     * Note that deletion of a subquery is also dependent on the check below
     * that its targetlist contains no set-returning functions.  Deletion from
     * a FROM list or inner JOIN is okay only if the subquery must return
     * exactly one row.
     */
    if (subquery->jointree->fromlist == NIL &&
        (subquery->jointree->quals != NULL ||
         !deletion_ok ||
         lowest_outer_join != NULL))
        return false;

    /*
     * If the subquery is LATERAL, check for pullup restrictions from that.
     */
    if (rte->lateral)
    {
        bool        restricted;
        Relids        safe_upper_varnos;

        /*
         * The subquery's WHERE and JOIN/ON quals mustn't contain any lateral
         * references to rels outside a higher outer join (including the case
         * where the outer join is within the subquery itself).  In such a
         * case, pulling up would result in a situation where we need to
         * postpone quals from below an outer join to above it, which is
         * probably completely wrong and in any case is a complication that
         * doesn't seem worth addressing at the moment.
         */
        if (lowest_outer_join != NULL)
        {
            restricted = true;
            safe_upper_varnos = get_relids_in_jointree((Node *) lowest_outer_join,
                                                       true);
        }
        else
        {
            restricted = false;
            safe_upper_varnos = NULL;    /* doesn't matter */
        }

        if (jointree_contains_lateral_outer_refs((Node *) subquery->jointree,
                                                 restricted, safe_upper_varnos))
            return false;

        /*
         * If there's an outer join above the LATERAL subquery, also disallow
         * pullup if the subquery's targetlist has any references to rels
         * outside the outer join, since these might get pulled into quals
         * above the subquery (but in or below the outer join) and then lead
         * to qual-postponement issues similar to the case checked for above.
         * (We wouldn't need to prevent pullup if no such references appear in
         * outer-query quals, but we don't have enough info here to check
         * that.  Also, maybe this restriction could be removed if we forced
         * such refs to be wrapped in PlaceHolderVars, even when they're below
         * the nearest outer join?    But it's a pretty hokey usage, so not
         * clear this is worth sweating over.)
         */
        if (lowest_outer_join != NULL)
        {
            Relids        lvarnos = pull_varnos_of_level((Node *) subquery->targetList, 1);

            if (!bms_is_subset(lvarnos, safe_upper_varnos))
                return false;
        }
    }

    /*
     * Don't pull up a subquery that has any volatile functions in its
     * targetlist.  Otherwise we might introduce multiple evaluations of these
     * functions, if they get copied to multiple places in the upper query,
     * leading to surprising results.  (Note: the PlaceHolderVar mechanism
     * doesn't quite guarantee single evaluation; else we could pull up anyway
     * and just wrap such items in PlaceHolderVars ...)
     */
    if (contain_volatile_functions((Node *) subquery->targetList))
        return false;

    return true;
}

/*
 * pull_up_simple_values
 *        Pull up a single simple VALUES RTE.
 *
 * jtnode is a RangeTblRef that has been identified as a simple VALUES RTE
 * by pull_up_subqueries.  We always return NULL indicating that the RTE
 * can be deleted entirely (all failure cases should have been detected by
 * is_simple_values()).
 *
 * rte is the RangeTblEntry referenced by jtnode.  Because of the limited
 * possible usage of VALUES RTEs, we do not need the remaining parameters
 * of pull_up_subqueries_recurse.
 */
static Node *
pull_up_simple_values(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte)
{
    Query       *parse = root->parse;
    int            varno = ((RangeTblRef *) jtnode)->rtindex;
    List       *values_list;
    List       *tlist;
    AttrNumber    attrno;
    pullup_replace_vars_context rvcontext;
    ListCell   *lc;

    Assert(rte->rtekind == RTE_VALUES);
    Assert(list_length(rte->values_lists) == 1);

    /*
     * Need a modifiable copy of the VALUES list to hack on, just in case it's
     * multiply referenced.
     */
    values_list = copyObject(linitial(rte->values_lists));

    /*
     * The VALUES RTE can't contain any Vars of level zero, let alone any that
     * are join aliases, so no need to flatten join alias Vars.
     */
    Assert(!contain_vars_of_level((Node *) values_list, 0));

    /*
     * Set up required context data for pullup_replace_vars.  In particular,
     * we have to make the VALUES list look like a subquery targetlist.
     */
    tlist = NIL;
    attrno = 1;
    foreach(lc, values_list)
    {
        tlist = lappend(tlist,
                        makeTargetEntry((Expr *) lfirst(lc),
                                        attrno,
                                        NULL,
                                        false));
        attrno++;
    }
    rvcontext.root = root;
    rvcontext.targetlist = tlist;
    rvcontext.target_rte = rte;
    rvcontext.relids = NULL;
    rvcontext.outer_hasSubLinks = &parse->hasSubLinks;
    rvcontext.varno = varno;
    rvcontext.need_phvs = false;
    rvcontext.wrap_non_vars = false;
    /* initialize cache array with indexes 0 .. length(tlist) */
    rvcontext.rv_cache = palloc0((list_length(tlist) + 1) *
                                 sizeof(Node *));

    /*
     * Replace all of the top query's references to the RTE's outputs with
     * copies of the adjusted VALUES expressions, being careful not to replace
     * any of the jointree structure. (This'd be a lot cleaner if we could use
     * query_tree_mutator.)  Much of this should be no-ops in the dummy Query
     * that surrounds a VALUES RTE, but it's not enough code to be worth
     * removing.
     */
    parse->targetList = (List *)
        pullup_replace_vars((Node *) parse->targetList, &rvcontext);
    parse->returningList = (List *)
        pullup_replace_vars((Node *) parse->returningList, &rvcontext);
    if (parse->onConflict)
    {
        parse->onConflict->onConflictSet = (List *)
            pullup_replace_vars((Node *) parse->onConflict->onConflictSet,
                                &rvcontext);
        parse->onConflict->onConflictWhere =
            pullup_replace_vars(parse->onConflict->onConflictWhere,
                                &rvcontext);

        /*
         * We assume ON CONFLICT's arbiterElems, arbiterWhere, exclRelTlist
         * can't contain any references to a subquery
         */
    }
    replace_vars_in_jointree((Node *) parse->jointree, &rvcontext, NULL);
    Assert(parse->setOperations == NULL);
    parse->havingQual = pullup_replace_vars(parse->havingQual, &rvcontext);

    /*
     * There should be no appendrels to fix, nor any join alias Vars, nor any
     * outer joins and hence no PlaceHolderVars.
     */
    Assert(root->append_rel_list == NIL);
    Assert(list_length(parse->rtable) == 1);
    Assert(root->join_info_list == NIL);
    Assert(root->placeholder_list == NIL);

    /*
     * Return NULL to signal deletion of the VALUES RTE from the parent
     * jointree (and set hasDeletedRTEs to ensure cleanup later).
     */
    root->hasDeletedRTEs = true;
    return NULL;
}

/*
 * is_simple_values
 *      Check a VALUES RTE in the range table to see if it's simple enough
 *      to pull up into the parent query.
 *
 * rte is the RTE_VALUES RangeTblEntry to check.
 * deletion_ok is TRUE if it'd be okay to delete the VALUES RTE entirely.
 */
static bool
is_simple_values(PlannerInfo *root, RangeTblEntry *rte, bool deletion_ok)
{
    Assert(rte->rtekind == RTE_VALUES);

    /*
     * We can only pull up a VALUES RTE if deletion_ok is TRUE.  It's
     * basically the same case as a sub-select with empty FROM list; see
     * comments in is_simple_subquery().
     */
    if (!deletion_ok)
        return false;

    /*
     * Also, there must be exactly one VALUES list, else it's not semantically
     * correct to delete the VALUES RTE.
     */
    if (list_length(rte->values_lists) != 1)
        return false;

    /*
     * Because VALUES can't appear under an outer join (or at least, we won't
     * try to pull it up if it does), we need not worry about LATERAL, nor
     * about validity of PHVs for the VALUES' outputs.
     */

    /*
     * Don't pull up a VALUES that contains any set-returning or volatile
     * functions.  Again, the considerations here are basically identical to
     * restrictions on a subquery's targetlist.
     */
    if (expression_returns_set((Node *) rte->values_lists) ||
        contain_volatile_functions((Node *) rte->values_lists))
        return false;

    /*
     * Do not pull up a VALUES that's not the only RTE in its parent query.
     * This is actually the only case that the parser will generate at the
     * moment, and assuming this is true greatly simplifies
     * pull_up_simple_values().
     */
    if (list_length(root->parse->rtable) != 1 ||
        rte != (RangeTblEntry *) linitial(root->parse->rtable))
        return false;

    return true;
}

/*
 * is_simple_union_all
 *      Check a subquery to see if it's a simple UNION ALL.
 *
 * We require all the setops to be UNION ALL (no mixing) and there can't be
 * any datatype coercions involved, ie, all the leaf queries must emit the
 * same datatypes.
 */
static bool
is_simple_union_all(Query *subquery)
{// #lizard forgives
    SetOperationStmt *topop;

    /* Let's just make sure it's a valid subselect ... */
    if (!IsA(subquery, Query) ||
        subquery->commandType != CMD_SELECT)
        elog(ERROR, "subquery is bogus");

    /* Is it a set-operation query at all? */
    topop = castNode(SetOperationStmt, subquery->setOperations);
    if (!topop)
        return false;

    /* Can't handle ORDER BY, LIMIT/OFFSET, locking, or WITH */
    if (subquery->sortClause ||
        subquery->limitOffset ||
        subquery->limitCount ||
        subquery->rowMarks ||
        subquery->cteList)
        return false;

    /* Recursively check the tree of set operations */
    return is_simple_union_all_recurse((Node *) topop, subquery,
                                       topop->colTypes);
}

static bool
is_simple_union_all_recurse(Node *setOp, Query *setOpQuery, List *colTypes)
{
    if (IsA(setOp, RangeTblRef))
    {
        RangeTblRef *rtr = (RangeTblRef *) setOp;
        RangeTblEntry *rte = rt_fetch(rtr->rtindex, setOpQuery->rtable);
        Query       *subquery = rte->subquery;

        Assert(subquery != NULL);

        /* Leaf nodes are OK if they match the toplevel column types */
        /* We don't have to compare typmods or collations here */
        return tlist_same_datatypes(subquery->targetList, colTypes, true);
    }
    else if (IsA(setOp, SetOperationStmt))
    {
        SetOperationStmt *op = (SetOperationStmt *) setOp;

        /* Must be UNION ALL */
        if (op->op != SETOP_UNION || !op->all)
            return false;

        /* Recurse to check inputs */
        return is_simple_union_all_recurse(op->larg, setOpQuery, colTypes) &&
            is_simple_union_all_recurse(op->rarg, setOpQuery, colTypes);
    }
    else
    {
        elog(ERROR, "unrecognized node type: %d",
             (int) nodeTag(setOp));
        return false;            /* keep compiler quiet */
    }
}

/*
 * is_safe_append_member
 *      Check a subquery that is a leaf of a UNION ALL appendrel to see if it's
 *      safe to pull up.
 */
static bool
is_safe_append_member(Query *subquery)
{
    FromExpr   *jtnode;

    /*
     * It's only safe to pull up the child if its jointree contains exactly
     * one RTE, else the AppendRelInfo data structure breaks. The one base RTE
     * could be buried in several levels of FromExpr, however.
     *
     * Also, the child can't have any WHERE quals because there's no place to
     * put them in an appendrel.  (This is a bit annoying...) If we didn't
     * need to check this, we'd just test whether get_relids_in_jointree()
     * yields a singleton set, to be more consistent with the coding of
     * fix_append_rel_relids().
     */
    jtnode = subquery->jointree;
    while (IsA(jtnode, FromExpr))
    {
        if (jtnode->quals != NULL)
            return false;
        if (list_length(jtnode->fromlist) != 1)
            return false;
        jtnode = linitial(jtnode->fromlist);
    }
    if (!IsA(jtnode, RangeTblRef))
        return false;

    return true;
}

/*
 * jointree_contains_lateral_outer_refs
 *        Check for disallowed lateral references in a jointree's quals
 *
 * If restricted is false, all level-1 Vars are allowed (but we still must
 * search the jointree, since it might contain outer joins below which there
 * will be restrictions).  If restricted is true, return TRUE when any qual
 * in the jointree contains level-1 Vars coming from outside the rels listed
 * in safe_upper_varnos.
 */
static bool
jointree_contains_lateral_outer_refs(Node *jtnode, bool restricted,
                                     Relids safe_upper_varnos)
{// #lizard forgives
    if (jtnode == NULL)
        return false;
    if (IsA(jtnode, RangeTblRef))
        return false;
    else if (IsA(jtnode, FromExpr))
    {
        FromExpr   *f = (FromExpr *) jtnode;
        ListCell   *l;

        /* First, recurse to check child joins */
        foreach(l, f->fromlist)
        {
            if (jointree_contains_lateral_outer_refs(lfirst(l),
                                                     restricted,
                                                     safe_upper_varnos))
                return true;
        }

        /* Then check the top-level quals */
        if (restricted &&
            !bms_is_subset(pull_varnos_of_level(f->quals, 1),
                           safe_upper_varnos))
            return true;
    }
    else if (IsA(jtnode, JoinExpr))
    {
        JoinExpr   *j = (JoinExpr *) jtnode;

        /*
         * If this is an outer join, we mustn't allow any upper lateral
         * references in or below it.
         */
        if (j->jointype != JOIN_INNER)
        {
            restricted = true;
            safe_upper_varnos = NULL;
        }

        /* Check the child joins */
        if (jointree_contains_lateral_outer_refs(j->larg,
                                                 restricted,
                                                 safe_upper_varnos))
            return true;
        if (jointree_contains_lateral_outer_refs(j->rarg,
                                                 restricted,
                                                 safe_upper_varnos))
            return true;

        /* Check the JOIN's qual clauses */
        if (restricted &&
            !bms_is_subset(pull_varnos_of_level(j->quals, 1),
                           safe_upper_varnos))
            return true;
    }
    else
        elog(ERROR, "unrecognized node type: %d",
             (int) nodeTag(jtnode));
    return false;
}

/*
 * Helper routine for pull_up_subqueries: do pullup_replace_vars on every
 * expression in the jointree, without changing the jointree structure itself.
 * Ugly, but there's no other way...
 *
 * If we are at or below lowest_nulling_outer_join, we can suppress use of
 * PlaceHolderVars wrapped around the replacement expressions.
 */
static void
replace_vars_in_jointree(Node *jtnode,
                         pullup_replace_vars_context *context,
                         JoinExpr *lowest_nulling_outer_join)
{// #lizard forgives
    if (jtnode == NULL)
        return;
    if (IsA(jtnode, RangeTblRef))
    {
        /*
         * If the RangeTblRef refers to a LATERAL subquery (that isn't the
         * same subquery we're pulling up), it might contain references to the
         * target subquery, which we must replace.  We drive this from the
         * jointree scan, rather than a scan of the rtable, for a couple of
         * reasons: we can avoid processing no-longer-referenced RTEs, and we
         * can use the appropriate setting of need_phvs depending on whether
         * the RTE is above possibly-nulling outer joins or not.
         */
        int            varno = ((RangeTblRef *) jtnode)->rtindex;

        if (varno != context->varno)    /* ignore target subquery itself */
        {
            RangeTblEntry *rte = rt_fetch(varno, context->root->parse->rtable);

            Assert(rte != context->target_rte);
            if (rte->lateral)
            {
                switch (rte->rtekind)
                {
                    case RTE_RELATION:
                        /* shouldn't be marked LATERAL unless tablesample */
                        Assert(rte->tablesample);
                        rte->tablesample = (TableSampleClause *)
                            pullup_replace_vars((Node *) rte->tablesample,
                                                context);
                        break;
                    case RTE_SUBQUERY:
                        rte->subquery =
                            pullup_replace_vars_subquery(rte->subquery,
                                                         context);
                        break;
                    case RTE_FUNCTION:
                        rte->functions = (List *)
                            pullup_replace_vars((Node *) rte->functions,
                                                context);
                        break;
                    case RTE_TABLEFUNC:
                        rte->tablefunc = (TableFunc *)
                            pullup_replace_vars((Node *) rte->tablefunc,
                                                context);
                        break;
                    case RTE_VALUES:
                        rte->values_lists = (List *)
                            pullup_replace_vars((Node *) rte->values_lists,
                                                context);
                        break;
                    case RTE_JOIN:
                    case RTE_CTE:
#ifdef XCP
                    case RTE_REMOTE_DUMMY:
#endif                    
                    case RTE_NAMEDTUPLESTORE:
                        /* these shouldn't be marked LATERAL */
                        Assert(false);
                        break;
                }
            }
        }
    }
    else if (IsA(jtnode, FromExpr))
    {
        FromExpr   *f = (FromExpr *) jtnode;
        ListCell   *l;

        foreach(l, f->fromlist)
            replace_vars_in_jointree(lfirst(l), context,
                                     lowest_nulling_outer_join);
        f->quals = pullup_replace_vars(f->quals, context);
    }
    else if (IsA(jtnode, JoinExpr))
    {
        JoinExpr   *j = (JoinExpr *) jtnode;
        bool        save_need_phvs = context->need_phvs;

        if (j == lowest_nulling_outer_join)
        {
            /* no more PHVs in or below this join */
            context->need_phvs = false;
            lowest_nulling_outer_join = NULL;
        }
        replace_vars_in_jointree(j->larg, context, lowest_nulling_outer_join);
        replace_vars_in_jointree(j->rarg, context, lowest_nulling_outer_join);
        j->quals = pullup_replace_vars(j->quals, context);

        /*
         * We don't bother to update the colvars list, since it won't be used
         * again ...
         */
        context->need_phvs = save_need_phvs;
    }
    else
        elog(ERROR, "unrecognized node type: %d",
             (int) nodeTag(jtnode));
}

/*
 * Apply pullup variable replacement throughout an expression tree
 *
 * Returns a modified copy of the tree, so this can't be used where we
 * need to do in-place replacement.
 */
static Node *
pullup_replace_vars(Node *expr, pullup_replace_vars_context *context)
{
    return replace_rte_variables(expr,
                                 context->varno, 0,
                                 pullup_replace_vars_callback,
                                 (void *) context,
                                 context->outer_hasSubLinks);
}

static Node *
pullup_replace_vars_callback(Var *var,
                             replace_rte_variables_context *context)
{// #lizard forgives
    pullup_replace_vars_context *rcon = (pullup_replace_vars_context *) context->callback_arg;
    int            varattno = var->varattno;
    Node       *newnode;

    /*
     * If PlaceHolderVars are needed, we cache the modified expressions in
     * rcon->rv_cache[].  This is not in hopes of any material speed gain
     * within this function, but to avoid generating identical PHVs with
     * different IDs.  That would result in duplicate evaluations at runtime,
     * and possibly prevent optimizations that rely on recognizing different
     * references to the same subquery output as being equal().  So it's worth
     * a bit of extra effort to avoid it.
     */
    if (rcon->need_phvs &&
        varattno >= InvalidAttrNumber &&
        varattno <= list_length(rcon->targetlist) &&
        rcon->rv_cache[varattno] != NULL)
    {
        /* Just copy the entry and fall through to adjust its varlevelsup */
        newnode = copyObject(rcon->rv_cache[varattno]);
    }
    else if (varattno == InvalidAttrNumber)
    {
        /* Must expand whole-tuple reference into RowExpr */
        RowExpr    *rowexpr;
        List       *colnames;
        List       *fields;
        bool        save_need_phvs = rcon->need_phvs;
        int            save_sublevelsup = context->sublevels_up;

        /*
         * If generating an expansion for a var of a named rowtype (ie, this
         * is a plain relation RTE), then we must include dummy items for
         * dropped columns.  If the var is RECORD (ie, this is a JOIN), then
         * omit dropped columns. Either way, attach column names to the
         * RowExpr for use of ruleutils.c.
         *
         * In order to be able to cache the results, we always generate the
         * expansion with varlevelsup = 0, and then adjust if needed.
         */
        expandRTE(rcon->target_rte,
                  var->varno, 0 /* not varlevelsup */ , var->location,
                  (var->vartype != RECORDOID),
                  &colnames, &fields);
        /* Adjust the generated per-field Vars, but don't insert PHVs */
        rcon->need_phvs = false;
        context->sublevels_up = 0;    /* to match the expandRTE output */
        fields = (List *) replace_rte_variables_mutator((Node *) fields,
                                                        context);
        rcon->need_phvs = save_need_phvs;
        context->sublevels_up = save_sublevelsup;

        rowexpr = makeNode(RowExpr);
        rowexpr->args = fields;
        rowexpr->row_typeid = var->vartype;
        rowexpr->row_format = COERCE_IMPLICIT_CAST;
        rowexpr->colnames = colnames;
        rowexpr->location = var->location;
        newnode = (Node *) rowexpr;

        /*
         * Insert PlaceHolderVar if needed.  Notice that we are wrapping one
         * PlaceHolderVar around the whole RowExpr, rather than putting one
         * around each element of the row.  This is because we need the
         * expression to yield NULL, not ROW(NULL,NULL,...) when it is forced
         * to null by an outer join.
         */
        if (rcon->need_phvs)
        {
            /* RowExpr is certainly not strict, so always need PHV */
            newnode = (Node *)
                make_placeholder_expr(rcon->root,
                                      (Expr *) newnode,
                                      bms_make_singleton(rcon->varno));
            /* cache it with the PHV, and with varlevelsup still zero */
            rcon->rv_cache[InvalidAttrNumber] = copyObject(newnode);
        }
    }
#ifdef PGXC
    else if (varattno == XC_NodeIdAttributeNumber)
    {
        /* We don't need to change the entry for xc_node_id */
        newnode = NULL;
    }
#endif
    else
    {
        /* Normal case referencing one targetlist element */
        TargetEntry *tle = get_tle_by_resno(rcon->targetlist, varattno);

        if (tle == NULL)        /* shouldn't happen */
            elog(ERROR, "could not find attribute %d in subquery targetlist",
                 varattno);

        /* Make a copy of the tlist item to return */
        newnode = (Node *) copyObject(tle->expr);

        /* Insert PlaceHolderVar if needed */
        if (rcon->need_phvs)
        {
            bool        wrap;

            if (newnode && IsA(newnode, Var) &&
                ((Var *) newnode)->varlevelsup == 0)
            {
                /*
                 * Simple Vars always escape being wrapped, unless they are
                 * lateral references to something outside the subquery being
                 * pulled up.  (Even then, we could omit the PlaceHolderVar if
                 * the referenced rel is under the same lowest outer join, but
                 * it doesn't seem worth the trouble to check that.)
                 */
                if (rcon->target_rte->lateral &&
                    !bms_is_member(((Var *) newnode)->varno, rcon->relids))
                    wrap = true;
                else
                    wrap = false;
            }
            else if (newnode && IsA(newnode, PlaceHolderVar) &&
                     ((PlaceHolderVar *) newnode)->phlevelsup == 0)
            {
                /* No need to wrap a PlaceHolderVar with another one, either */
                wrap = false;
            }
            else if (rcon->wrap_non_vars)
            {
                /* Wrap all non-Vars in a PlaceHolderVar */
                wrap = true;
            }
            else
            {
                /*
                 * If it contains a Var of the subquery being pulled up, and
                 * does not contain any non-strict constructs, then it's
                 * certainly nullable so we don't need to insert a
                 * PlaceHolderVar.
                 *
                 * This analysis could be tighter: in particular, a non-strict
                 * construct hidden within a lower-level PlaceHolderVar is not
                 * reason to add another PHV.  But for now it doesn't seem
                 * worth the code to be more exact.
                 *
                 * Note: in future maybe we should insert a PlaceHolderVar
                 * anyway, if the tlist item is expensive to evaluate?
                 *
                 * For a LATERAL subquery, we have to check the actual var
                 * membership of the node, but if it's non-lateral then any
                 * level-zero var must belong to the subquery.
                 */
                if ((rcon->target_rte->lateral ?
                     bms_overlap(pull_varnos((Node *) newnode), rcon->relids) :
                     contain_vars_of_level((Node *) newnode, 0)) &&
                    !contain_nonstrict_functions((Node *) newnode))
                {
                    /* No wrap needed */
                    wrap = false;
                }
                else
                {
                    /* Else wrap it in a PlaceHolderVar */
                    wrap = true;
                }
            }

            if (wrap)
                newnode = (Node *)
                    make_placeholder_expr(rcon->root,
                                          (Expr *) newnode,
                                          bms_make_singleton(rcon->varno));

            /*
             * Cache it if possible (ie, if the attno is in range, which it
             * probably always should be).  We can cache the value even if we
             * decided we didn't need a PHV, since this result will be
             * suitable for any request that has need_phvs.
             */
            if (varattno > InvalidAttrNumber &&
                varattno <= list_length(rcon->targetlist))
                rcon->rv_cache[varattno] = copyObject(newnode);
        }
    }

    /* Must adjust varlevelsup if tlist item is from higher query */
    if (var->varlevelsup > 0)
        IncrementVarSublevelsUp(newnode, var->varlevelsup, 0);

    return newnode;
}

/*
 * Apply pullup variable replacement to a subquery
 *
 * This needs to be different from pullup_replace_vars() because
 * replace_rte_variables will think that it shouldn't increment sublevels_up
 * before entering the Query; so we need to call it with sublevels_up == 1.
 */
static Query *
pullup_replace_vars_subquery(Query *query,
                             pullup_replace_vars_context *context)
{
    Assert(IsA(query, Query));
    return (Query *) replace_rte_variables((Node *) query,
                                           context->varno, 1,
                                           pullup_replace_vars_callback,
                                           (void *) context,
                                           NULL);
}

/*
 * pull_up_subqueries_cleanup
 *        Recursively fix up jointree after deletion of some subqueries.
 *
 * The jointree now contains some NULL subtrees, which we need to get rid of.
 * In a FromExpr, just rebuild the child-node list with null entries deleted.
 * In an inner JOIN, replace the JoinExpr node with a one-child FromExpr.
 */
static Node *
pull_up_subqueries_cleanup(Node *jtnode)
{// #lizard forgives
    Assert(jtnode != NULL);
    if (IsA(jtnode, RangeTblRef))
    {
        /* Nothing to do at leaf nodes. */
    }
    else if (IsA(jtnode, FromExpr))
    {
        FromExpr   *f = (FromExpr *) jtnode;
        List       *newfrom = NIL;
        ListCell   *l;

        foreach(l, f->fromlist)
        {
            Node       *child = (Node *) lfirst(l);

            if (child == NULL)
                continue;
            child = pull_up_subqueries_cleanup(child);
            newfrom = lappend(newfrom, child);
        }
        f->fromlist = newfrom;
    }
    else if (IsA(jtnode, JoinExpr))
    {
        JoinExpr   *j = (JoinExpr *) jtnode;

        if (j->larg)
            j->larg = pull_up_subqueries_cleanup(j->larg);
        if (j->rarg)
            j->rarg = pull_up_subqueries_cleanup(j->rarg);
        if (j->larg == NULL)
        {
            Assert(j->jointype == JOIN_INNER);
            Assert(j->rarg != NULL);
            return (Node *) makeFromExpr(list_make1(j->rarg), j->quals);
        }
        else if (j->rarg == NULL)
        {
            Assert(j->jointype == JOIN_INNER);
            return (Node *) makeFromExpr(list_make1(j->larg), j->quals);
        }
    }
    else
        elog(ERROR, "unrecognized node type: %d",
             (int) nodeTag(jtnode));
    return jtnode;
}


/*
 * flatten_simple_union_all
 *        Try to optimize top-level UNION ALL structure into an appendrel
 *
 * If a query's setOperations tree consists entirely of simple UNION ALL
 * operations, flatten it into an append relation, which we can process more
 * intelligently than the general setops case.  Otherwise, do nothing.
 *
 * In most cases, this can succeed only for a top-level query, because for a
 * subquery in FROM, the parent query's invocation of pull_up_subqueries would
 * already have flattened the UNION via pull_up_simple_union_all.  But there
 * are a few cases we can support here but not in that code path, for example
 * when the subquery also contains ORDER BY.
 */
void
flatten_simple_union_all(PlannerInfo *root)
{
    Query       *parse = root->parse;
    SetOperationStmt *topop;
    Node       *leftmostjtnode;
    int            leftmostRTI;
    RangeTblEntry *leftmostRTE;
    int            childRTI;
    RangeTblEntry *childRTE;
    RangeTblRef *rtr;

    /* Shouldn't be called unless query has setops */
    topop = castNode(SetOperationStmt, parse->setOperations);
    Assert(topop);

    /* Can't optimize away a recursive UNION */
    if (root->hasRecursion)
        return;

    /*
     * Recursively check the tree of set operations.  If not all UNION ALL
     * with identical column types, punt.
     */
    if (!is_simple_union_all_recurse((Node *) topop, parse, topop->colTypes))
        return;

    /*
     * Locate the leftmost leaf query in the setops tree.  The upper query's
     * Vars all refer to this RTE (see transformSetOperationStmt).
     */
    leftmostjtnode = topop->larg;
    while (leftmostjtnode && IsA(leftmostjtnode, SetOperationStmt))
        leftmostjtnode = ((SetOperationStmt *) leftmostjtnode)->larg;
    Assert(leftmostjtnode && IsA(leftmostjtnode, RangeTblRef));
    leftmostRTI = ((RangeTblRef *) leftmostjtnode)->rtindex;
    leftmostRTE = rt_fetch(leftmostRTI, parse->rtable);
    Assert(leftmostRTE->rtekind == RTE_SUBQUERY);

    /*
     * Make a copy of the leftmost RTE and add it to the rtable.  This copy
     * will represent the leftmost leaf query in its capacity as a member of
     * the appendrel.  The original will represent the appendrel as a whole.
     * (We must do things this way because the upper query's Vars have to be
     * seen as referring to the whole appendrel.)
     */
    childRTE = copyObject(leftmostRTE);
    parse->rtable = lappend(parse->rtable, childRTE);
    childRTI = list_length(parse->rtable);

    /* Modify the setops tree to reference the child copy */
    ((RangeTblRef *) leftmostjtnode)->rtindex = childRTI;

    /* Modify the formerly-leftmost RTE to mark it as an appendrel parent */
    leftmostRTE->inh = true;

    /*
     * Form a RangeTblRef for the appendrel, and insert it into FROM.  The top
     * Query of a setops tree should have had an empty FromClause initially.
     */
    rtr = makeNode(RangeTblRef);
    rtr->rtindex = leftmostRTI;
    Assert(parse->jointree->fromlist == NIL);
    parse->jointree->fromlist = list_make1(rtr);

    /*
     * Now pretend the query has no setops.  We must do this before trying to
     * do subquery pullup, because of Assert in pull_up_simple_subquery.
     */
    parse->setOperations = NULL;

    /*
     * Build AppendRelInfo information, and apply pull_up_subqueries to the
     * leaf queries of the UNION ALL.  (We must do that now because they
     * weren't previously referenced by the jointree, and so were missed by
     * the main invocation of pull_up_subqueries.)
     */
    pull_up_union_leaf_queries((Node *) topop, root, leftmostRTI, parse, 0);
}


/*
 * reduce_outer_joins
 *        Attempt to reduce outer joins to plain inner joins.
 *
 * The idea here is that given a query like
 *        SELECT ... FROM a LEFT JOIN b ON (...) WHERE b.y = 42;
 * we can reduce the LEFT JOIN to a plain JOIN if the "=" operator in WHERE
 * is strict.  The strict operator will always return NULL, causing the outer
 * WHERE to fail, on any row where the LEFT JOIN filled in NULLs for b's
 * columns.  Therefore, there's no need for the join to produce null-extended
 * rows in the first place --- which makes it a plain join not an outer join.
 * (This scenario may not be very likely in a query written out by hand, but
 * it's reasonably likely when pushing quals down into complex views.)
 *
 * More generally, an outer join can be reduced in strength if there is a
 * strict qual above it in the qual tree that constrains a Var from the
 * nullable side of the join to be non-null.  (For FULL joins this applies
 * to each side separately.)
 *
 * Another transformation we apply here is to recognize cases like
 *        SELECT ... FROM a LEFT JOIN b ON (a.x = b.y) WHERE b.y IS NULL;
 * If the join clause is strict for b.y, then only null-extended rows could
 * pass the upper WHERE, and we can conclude that what the query is really
 * specifying is an anti-semijoin.  We change the join type from JOIN_LEFT
 * to JOIN_ANTI.  The IS NULL clause then becomes redundant, and must be
 * removed to prevent bogus selectivity calculations, but we leave it to
 * distribute_qual_to_rels to get rid of such clauses.
 *
 * Also, we get rid of JOIN_RIGHT cases by flipping them around to become
 * JOIN_LEFT.  This saves some code here and in some later planner routines,
 * but the main reason to do it is to not need to invent a JOIN_REVERSE_ANTI
 * join type.
 *
 * To ease recognition of strict qual clauses, we require this routine to be
 * run after expression preprocessing (i.e., qual canonicalization and JOIN
 * alias-var expansion).
 */
void
reduce_outer_joins(PlannerInfo *root)
{
    reduce_outer_joins_state *state;

    /*
     * To avoid doing strictness checks on more quals than necessary, we want
     * to stop descending the jointree as soon as there are no outer joins
     * below our current point.  This consideration forces a two-pass process.
     * The first pass gathers information about which base rels appear below
     * each side of each join clause, and about whether there are outer
     * join(s) below each side of each join clause. The second pass examines
     * qual clauses and changes join types as it descends the tree.
     */
    state = reduce_outer_joins_pass1((Node *) root->parse->jointree);

    /* planner.c shouldn't have called me if no outer joins */
    if (state == NULL || !state->contains_outer)
        elog(ERROR, "so where are the outer joins?");

    reduce_outer_joins_pass2((Node *) root->parse->jointree,
                             state, root, NULL, NIL, NIL);
}

/*
 * reduce_outer_joins_pass1 - phase 1 data collection
 *
 * Returns a state node describing the given jointree node.
 */
static reduce_outer_joins_state *
reduce_outer_joins_pass1(Node *jtnode)
{
    reduce_outer_joins_state *result;

    result = (reduce_outer_joins_state *)
        palloc(sizeof(reduce_outer_joins_state));
    result->relids = NULL;
    result->contains_outer = false;
    result->sub_states = NIL;

    if (jtnode == NULL)
        return result;
    if (IsA(jtnode, RangeTblRef))
    {
        int            varno = ((RangeTblRef *) jtnode)->rtindex;

        result->relids = bms_make_singleton(varno);
    }
    else if (IsA(jtnode, FromExpr))
    {
        FromExpr   *f = (FromExpr *) jtnode;
        ListCell   *l;

        foreach(l, f->fromlist)
        {
            reduce_outer_joins_state *sub_state;

            sub_state = reduce_outer_joins_pass1(lfirst(l));
            result->relids = bms_add_members(result->relids,
                                             sub_state->relids);
            result->contains_outer |= sub_state->contains_outer;
            result->sub_states = lappend(result->sub_states, sub_state);
        }
    }
    else if (IsA(jtnode, JoinExpr))
    {
        JoinExpr   *j = (JoinExpr *) jtnode;
        reduce_outer_joins_state *sub_state;

        /* join's own RT index is not wanted in result->relids */
        if (IS_OUTER_JOIN(j->jointype))
            result->contains_outer = true;

        sub_state = reduce_outer_joins_pass1(j->larg);
        result->relids = bms_add_members(result->relids,
                                         sub_state->relids);
        result->contains_outer |= sub_state->contains_outer;
        result->sub_states = lappend(result->sub_states, sub_state);

        sub_state = reduce_outer_joins_pass1(j->rarg);
        result->relids = bms_add_members(result->relids,
                                         sub_state->relids);
        result->contains_outer |= sub_state->contains_outer;
        result->sub_states = lappend(result->sub_states, sub_state);
    }
    else
        elog(ERROR, "unrecognized node type: %d",
             (int) nodeTag(jtnode));
    return result;
}

/*
 * reduce_outer_joins_pass2 - phase 2 processing
 *
 *    jtnode: current jointree node
 *    state: state data collected by phase 1 for this node
 *    root: toplevel planner state
 *    nonnullable_rels: set of base relids forced non-null by upper quals
 *    nonnullable_vars: list of Vars forced non-null by upper quals
 *    forced_null_vars: list of Vars forced null by upper quals
 */
static void
reduce_outer_joins_pass2(Node *jtnode,
						 reduce_outer_joins_state *state,
						 PlannerInfo *root,
						 Relids nonnullable_rels,
						 List *nonnullable_vars,
						 List *forced_null_vars)
{
	/*
	 * pass 2 should never descend as far as an empty subnode or base rel,
	 * because it's only called on subtrees marked as contains_outer.
	 */
	if (jtnode == NULL)
		elog(ERROR, "reached empty jointree");
	if (IsA(jtnode, RangeTblRef))
		elog(ERROR, "reached base rel");
	else if (IsA(jtnode, FromExpr))
	{
		FromExpr   *f = (FromExpr *) jtnode;
		ListCell   *l;
		ListCell   *s;
		Relids		pass_nonnullable_rels;
		List	   *pass_nonnullable_vars;
		List	   *pass_forced_null_vars;

		/* Scan quals to see if we can add any constraints */
		pass_nonnullable_rels = find_nonnullable_rels(f->quals);
		pass_nonnullable_rels = bms_add_members(pass_nonnullable_rels,
												nonnullable_rels);
		/* NB: we rely on list_concat to not damage its second argument */
		pass_nonnullable_vars = find_nonnullable_vars(f->quals);
		pass_nonnullable_vars = list_concat(pass_nonnullable_vars,
											nonnullable_vars);
		pass_forced_null_vars = find_forced_null_vars(f->quals);
		pass_forced_null_vars = list_concat(pass_forced_null_vars,
											forced_null_vars);
		/* And recurse --- but only into interesting subtrees */
		Assert(list_length(f->fromlist) == list_length(state->sub_states));
		forboth(l, f->fromlist, s, state->sub_states)
		{
			reduce_outer_joins_state *sub_state = lfirst(s);

			if (sub_state->contains_outer)
				reduce_outer_joins_pass2(lfirst(l), sub_state, root,
										 pass_nonnullable_rels,
										 pass_nonnullable_vars,
										 pass_forced_null_vars);
		}
		bms_free(pass_nonnullable_rels);
		/* can't so easily clean up var lists, unfortunately */
	}
	else if (IsA(jtnode, JoinExpr))
	{
		JoinExpr   *j = (JoinExpr *) jtnode;
		int			rtindex = j->rtindex;
		JoinType	jointype = j->jointype;
		reduce_outer_joins_state *left_state = linitial(state->sub_states);
		reduce_outer_joins_state *right_state = lsecond(state->sub_states);
		List	   *local_nonnullable_vars = NIL;
		bool		computed_local_nonnullable_vars = false;

		/* Can we simplify this join? */
		switch (jointype)
		{
			case JOIN_INNER:
				break;
			case JOIN_LEFT:
				if (bms_overlap(nonnullable_rels, right_state->relids))
					jointype = JOIN_INNER;
				break;
			case JOIN_RIGHT:
				if (bms_overlap(nonnullable_rels, left_state->relids))
					jointype = JOIN_INNER;
				break;
			case JOIN_FULL:
				if (bms_overlap(nonnullable_rels, left_state->relids))
				{
					if (bms_overlap(nonnullable_rels, right_state->relids))
						jointype = JOIN_INNER;
					else
						jointype = JOIN_LEFT;
				}
				else
				{
					if (bms_overlap(nonnullable_rels, right_state->relids))
						jointype = JOIN_RIGHT;
				}
				break;
			case JOIN_SEMI:
			case JOIN_ANTI:
			case JOIN_LEFT_SCALAR:
			case JOIN_LEFT_SEMI:

				/*
				 * These could only have been introduced by pull_up_sublinks,
				 * so there's no way that upper quals could refer to their
				 * righthand sides, and no point in checking.
				 */
				break;
			default:
				elog(ERROR, "unrecognized join type: %d",
					 (int) jointype);
				break;
		}

		/*
		 * Convert JOIN_RIGHT to JOIN_LEFT.  Note that in the case where we
		 * reduced JOIN_FULL to JOIN_RIGHT, this will mean the JoinExpr no
		 * longer matches the internal ordering of any CoalesceExpr's built to
		 * represent merged join variables.  We don't care about that at
		 * present, but be wary of it ...
		 */
		if (jointype == JOIN_RIGHT)
		{
			Node	   *tmparg;

			tmparg = j->larg;
			j->larg = j->rarg;
			j->rarg = tmparg;
			jointype = JOIN_LEFT;
			right_state = linitial(state->sub_states);
			left_state = lsecond(state->sub_states);
		}

		/*
		 * See if we can reduce JOIN_LEFT to JOIN_ANTI.  This is the case if
		 * the join's own quals are strict for any var that was forced null by
		 * higher qual levels.  NOTE: there are other ways that we could
		 * detect an anti-join, in particular if we were to check whether Vars
		 * coming from the RHS must be non-null because of table constraints.
		 * That seems complicated and expensive though (in particular, one
		 * would have to be wary of lower outer joins). For the moment this
		 * seems sufficient.
		 */
		if (jointype == JOIN_LEFT)
		{
			List	   *overlap;

			local_nonnullable_vars = find_nonnullable_vars(j->quals);
			computed_local_nonnullable_vars = true;

			/*
			 * It's not sufficient to check whether local_nonnullable_vars and
			 * forced_null_vars overlap: we need to know if the overlap
			 * includes any RHS variables.
			 */
			overlap = list_intersection(local_nonnullable_vars,
										forced_null_vars);
			if (overlap != NIL &&
				bms_overlap(pull_varnos((Node *) overlap),
							right_state->relids))
				jointype = JOIN_ANTI;
		}

		/* Apply the jointype change, if any, to both jointree node and RTE */
		if (rtindex && jointype != j->jointype)
		{
			RangeTblEntry *rte = rt_fetch(rtindex, root->parse->rtable);

			Assert(rte->rtekind == RTE_JOIN);
			Assert(rte->jointype == j->jointype);
			rte->jointype = jointype;
		}
		j->jointype = jointype;

		/* Only recurse if there's more to do below here */
		if (left_state->contains_outer || right_state->contains_outer)
		{
			Relids		local_nonnullable_rels;
			List	   *local_forced_null_vars;
			Relids		pass_nonnullable_rels;
			List	   *pass_nonnullable_vars;
			List	   *pass_forced_null_vars;

			/*
			 * If this join is (now) inner, we can add any constraints its
			 * quals provide to those we got from above.  But if it is outer,
			 * we can pass down the local constraints only into the nullable
			 * side, because an outer join never eliminates any rows from its
			 * non-nullable side.  Also, there is no point in passing upper
			 * constraints into the nullable side, since if there were any
			 * we'd have been able to reduce the join.  (In the case of upper
			 * forced-null constraints, we *must not* pass them into the
			 * nullable side --- they either applied here, or not.) The upshot
			 * is that we pass either the local or the upper constraints,
			 * never both, to the children of an outer join.
			 *
			 * Note that a SEMI join works like an inner join here: it's okay
			 * to pass down both local and upper constraints.  (There can't be
			 * any upper constraints affecting its inner side, but it's not
			 * worth having a separate code path to avoid passing them.)
			 *
			 * At a FULL join we just punt and pass nothing down --- is it
			 * possible to be smarter?
			 */
			if (jointype != JOIN_FULL)
			{
				local_nonnullable_rels = find_nonnullable_rels(j->quals);
				if (!computed_local_nonnullable_vars)
					local_nonnullable_vars = find_nonnullable_vars(j->quals);
				local_forced_null_vars = find_forced_null_vars(j->quals);
#ifdef __OPENTENBASE__
                if (jointype == JOIN_INNER || jointype == JOIN_SEMI || jointype == JOIN_LEFT_SCALAR)
#else
				if (jointype == JOIN_INNER || jointype == JOIN_SEMI)
#endif
				{
					/* OK to merge upper and local constraints */
					local_nonnullable_rels = bms_add_members(local_nonnullable_rels,
															 nonnullable_rels);
					local_nonnullable_vars = list_concat(local_nonnullable_vars,
														 nonnullable_vars);
					local_forced_null_vars = list_concat(local_forced_null_vars,
														 forced_null_vars);
				}
			}
			else
			{
				/* no use in calculating these */
				local_nonnullable_rels = NULL;
				local_forced_null_vars = NIL;
			}

			if (left_state->contains_outer)
			{
				if (jointype == JOIN_INNER || jointype == JOIN_SEMI)
				{
					/* pass union of local and upper constraints */
					pass_nonnullable_rels = local_nonnullable_rels;
					pass_nonnullable_vars = local_nonnullable_vars;
					pass_forced_null_vars = local_forced_null_vars;
				}
				else if (jointype != JOIN_FULL) /* ie, LEFT or ANTI */
				{
					/* can't pass local constraints to non-nullable side */
					pass_nonnullable_rels = nonnullable_rels;
					pass_nonnullable_vars = nonnullable_vars;
					pass_forced_null_vars = forced_null_vars;
				}
				else
				{
					/* no constraints pass through JOIN_FULL */
					pass_nonnullable_rels = NULL;
					pass_nonnullable_vars = NIL;
					pass_forced_null_vars = NIL;
				}
				reduce_outer_joins_pass2(j->larg, left_state, root,
										 pass_nonnullable_rels,
										 pass_nonnullable_vars,
										 pass_forced_null_vars);
			}

			if (right_state->contains_outer)
			{
				if (jointype != JOIN_FULL)	/* ie, INNER/LEFT/SEMI/ANTI */
				{
					/* pass appropriate constraints, per comment above */
					pass_nonnullable_rels = local_nonnullable_rels;
					pass_nonnullable_vars = local_nonnullable_vars;
					pass_forced_null_vars = local_forced_null_vars;
				}
				else
				{
					/* no constraints pass through JOIN_FULL */
					pass_nonnullable_rels = NULL;
					pass_nonnullable_vars = NIL;
					pass_forced_null_vars = NIL;
				}
				reduce_outer_joins_pass2(j->rarg, right_state, root,
										 pass_nonnullable_rels,
										 pass_nonnullable_vars,
										 pass_forced_null_vars);
			}
			bms_free(local_nonnullable_rels);
		}
	}
	else
		elog(ERROR, "unrecognized node type: %d",
			 (int) nodeTag(jtnode));
}

/*
 * substitute_multiple_relids - adjust node relid sets after pulling up
 * a subquery
 *
 * Find any PlaceHolderVar nodes in the given tree that reference the
 * pulled-up relid, and change them to reference the replacement relid(s).
 *
 * NOTE: although this has the form of a walker, we cheat and modify the
 * nodes in-place.  This should be OK since the tree was copied by
 * pullup_replace_vars earlier.  Avoid scribbling on the original values of
 * the bitmapsets, though, because expression_tree_mutator doesn't copy those.
 */

typedef struct
{
    int            varno;
    int            sublevels_up;
    Relids        subrelids;
} substitute_multiple_relids_context;

static bool
substitute_multiple_relids_walker(Node *node,
                                  substitute_multiple_relids_context *context)
{
    if (node == NULL)
        return false;
    if (IsA(node, PlaceHolderVar))
    {
        PlaceHolderVar *phv = (PlaceHolderVar *) node;

        if (phv->phlevelsup == context->sublevels_up &&
            bms_is_member(context->varno, phv->phrels))
        {
            phv->phrels = bms_union(phv->phrels,
                                    context->subrelids);
            phv->phrels = bms_del_member(phv->phrels,
                                         context->varno);
        }
        /* fall through to examine children */
    }
    if (IsA(node, Query))
    {
        /* Recurse into subselects */
        bool        result;

        context->sublevels_up++;
        result = query_tree_walker((Query *) node,
                                   substitute_multiple_relids_walker,
                                   (void *) context, 0);
        context->sublevels_up--;
        return result;
    }
    /* Shouldn't need to handle planner auxiliary nodes here */
    Assert(!IsA(node, SpecialJoinInfo));
    Assert(!IsA(node, AppendRelInfo));
    Assert(!IsA(node, PlaceHolderInfo));
    Assert(!IsA(node, MinMaxAggInfo));

    return expression_tree_walker(node, substitute_multiple_relids_walker,
                                  (void *) context);
}

static void
substitute_multiple_relids(Node *node, int varno, Relids subrelids)
{
    substitute_multiple_relids_context context;

    context.varno = varno;
    context.sublevels_up = 0;
    context.subrelids = subrelids;

    /*
     * Must be prepared to start with a Query or a bare expression tree.
     */
    query_or_expression_tree_walker(node,
                                    substitute_multiple_relids_walker,
                                    (void *) &context,
                                    0);
}

/*
 * fix_append_rel_relids: update RT-index fields of AppendRelInfo nodes
 *
 * When we pull up a subquery, any AppendRelInfo references to the subquery's
 * RT index have to be replaced by the substituted relid (and there had better
 * be only one).  We also need to apply substitute_multiple_relids to their
 * translated_vars lists, since those might contain PlaceHolderVars.
 *
 * We assume we may modify the AppendRelInfo nodes in-place.
 */
static void
fix_append_rel_relids(List *append_rel_list, int varno, Relids subrelids)
{
    ListCell   *l;
    int            subvarno = -1;

    /*
     * We only want to extract the member relid once, but we mustn't fail
     * immediately if there are multiple members; it could be that none of the
     * AppendRelInfo nodes refer to it.  So compute it on first use. Note that
     * bms_singleton_member will complain if set is not singleton.
     */
    foreach(l, append_rel_list)
    {
        AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);

        /* The parent_relid shouldn't ever be a pullup target */
        Assert(appinfo->parent_relid != varno);

        if (appinfo->child_relid == varno)
        {
            if (subvarno < 0)
                subvarno = bms_singleton_member(subrelids);
            appinfo->child_relid = subvarno;
        }

        /* Also finish fixups for its translated vars */
        substitute_multiple_relids((Node *) appinfo->translated_vars,
                                   varno, subrelids);
    }
}

/*
 * get_relids_in_jointree: get set of RT indexes present in a jointree
 *
 * If include_joins is true, join RT indexes are included; if false,
 * only base rels are included.
 */
Relids
get_relids_in_jointree(Node *jtnode, bool include_joins)
{
    Relids        result = NULL;

    if (jtnode == NULL)
        return result;
    if (IsA(jtnode, RangeTblRef))
    {
        int            varno = ((RangeTblRef *) jtnode)->rtindex;

        result = bms_make_singleton(varno);
    }
    else if (IsA(jtnode, FromExpr))
    {
        FromExpr   *f = (FromExpr *) jtnode;
        ListCell   *l;

        foreach(l, f->fromlist)
        {
            result = bms_join(result,
                              get_relids_in_jointree(lfirst(l),
                                                     include_joins));
        }
    }
    else if (IsA(jtnode, JoinExpr))
    {
        JoinExpr   *j = (JoinExpr *) jtnode;

        result = get_relids_in_jointree(j->larg, include_joins);
        result = bms_join(result,
                          get_relids_in_jointree(j->rarg, include_joins));
        if (include_joins && j->rtindex)
            result = bms_add_member(result, j->rtindex);
    }
    else
        elog(ERROR, "unrecognized node type: %d",
             (int) nodeTag(jtnode));
    return result;
}

/*
 * get_relids_for_join: get set of base RT indexes making up a join
 */
Relids
get_relids_for_join(PlannerInfo *root, int joinrelid)
{
    Node       *jtnode;

    jtnode = find_jointree_node_for_rel((Node *) root->parse->jointree,
                                        joinrelid);
    if (!jtnode)
        elog(ERROR, "could not find join node %d", joinrelid);
    return get_relids_in_jointree(jtnode, false);
}

/*
 * find_jointree_node_for_rel: locate jointree node for a base or join RT index
 *
 * Returns NULL if not found
 */
static Node *
find_jointree_node_for_rel(Node *jtnode, int relid)
{// #lizard forgives
    if (jtnode == NULL)
        return NULL;
    if (IsA(jtnode, RangeTblRef))
    {
        int            varno = ((RangeTblRef *) jtnode)->rtindex;

        if (relid == varno)
            return jtnode;
    }
    else if (IsA(jtnode, FromExpr))
    {
        FromExpr   *f = (FromExpr *) jtnode;
        ListCell   *l;

        foreach(l, f->fromlist)
        {
            jtnode = find_jointree_node_for_rel(lfirst(l), relid);
            if (jtnode)
                return jtnode;
        }
    }
    else if (IsA(jtnode, JoinExpr))
    {
        JoinExpr   *j = (JoinExpr *) jtnode;

        if (relid == j->rtindex)
            return jtnode;
        jtnode = find_jointree_node_for_rel(j->larg, relid);
        if (jtnode)
            return jtnode;
        jtnode = find_jointree_node_for_rel(j->rarg, relid);
        if (jtnode)
            return jtnode;
    }
    else
        elog(ERROR, "unrecognized node type: %d",
             (int) nodeTag(jtnode));
    return NULL;
}
